Recombinant Ureaplasma parvum serovar 3 UPF0154 protein UU265 (UU265)

What is Ureaplasma parvum serovar 3 UPF0154 protein UU265?

UPF0154 protein UU265 is a 109-amino acid protein encoded by the UU265 gene in Ureaplasma parvum serovar 3. It belongs to the UPF0154 protein family, whose precise functions remain to be fully characterized. The complete amino acid sequence is:

MNFSSFIFKVSDVFKSVIHEASDVVTKADLDNANAHTHSLAVGLGIGIVLFLIAGLIIGY FISMKIMKRQLKKNPPISKDTIRMIYQQVGRKPSESQINEIYNRAVKQK

Sequence analysis suggests UU265 contains hydrophobic regions likely forming transmembrane domains, particularly in the LAVGLGIGIVLFLIAGLIIGY segment. This indicates it may function as a membrane-associated protein, potentially playing a role in the organism's interaction with host cells. The protein is of particular interest due to Ureaplasma parvum's association with reproductive pathologies, including preterm birth and infertility .

What structural characteristics define UPF0154 protein UU265?

UU265 displays several key structural features that inform its potential biological functions:

• Transmembrane domains: The protein contains hydrophobic segments consistent with membrane integration, suggesting localization to bacterial or host cell membranes.

• Charged regions: The C-terminal portion (QVGRKPSESQINEIYNRAVKQK) contains multiple charged amino acids that may facilitate protein-protein interactions or specific cellular functions.

• Size and topology: At 109 amino acids, it's a relatively small protein with predicted alpha-helical regions in the transmembrane domains and potentially more flexible regions elsewhere.

• Conservation pattern: Certain regions show higher conservation across Ureaplasma species, suggesting functional importance of these segments.

For experimental studies, recombinant UU265 is typically produced with an N-terminal His-tag, which facilitates purification while maintaining the protein's native structure and functional domains . This structural information guides experimental approaches for studying UU265's role in Ureaplasma parvum biology and pathogenesis.

How is recombinant UU265 protein produced for research applications?

Production of recombinant UPF0154 protein UU265 involves several critical steps to ensure proper expression, purification, and maintenance of the protein's native properties:

• Expression system: The protein is typically expressed in E. coli, which provides an efficient system for producing bacterial proteins while allowing for the addition of purification tags .

• Construct design:

  • The full coding sequence (amino acids 1-109) is cloned into an appropriate expression vector

  • An N-terminal His-tag is added to facilitate purification

  • Expression is controlled by an inducible promoter system

• Purification protocol:

  • Bacterial lysis under conditions that maintain protein solubility

  • Nickel affinity chromatography to capture the His-tagged protein

  • Additional purification steps may include ion exchange or size exclusion chromatography

  • Quality control via SDS-PAGE typically confirms >90% purity

• Final processing:

  • Buffer exchange into a Tris/PBS-based buffer with 6% Trehalose at pH 8.0

  • Lyophilization for long-term stability

  • QC testing to confirm identity, purity, and structural integrity

This methodology provides purified protein suitable for a range of applications, from structural studies to functional assays investigating Ureaplasma parvum pathogenesis mechanisms.

What are the optimal storage conditions for recombinant UU265 protein?

Proper storage of recombinant UPF0154 protein UU265 is critical for maintaining its structural integrity and biological activity. The recommended storage conditions are:

• Long-term storage (lyophilized form):

  • Store at -20°C to -80°C in sealed containers to prevent moisture absorption

  • The lyophilized powder contains 6% Trehalose as a stabilizing agent to maintain protein structure during freeze-drying and storage

• Reconstituted protein storage:

  • Short-term use (up to one week): Store at 4°C

  • Longer-term storage: Aliquot and store at -20°C to -80°C

  • Add glycerol (5-50% final concentration, typically 50%) to prevent freeze damage

• Critical considerations:

  • Avoid repeated freeze-thaw cycles, as they significantly compromise protein integrity

  • Centrifuge vials briefly before opening to collect the contents at the bottom

  • Maintain sterile conditions to prevent microbial contamination

Following these guidelines ensures maximum retention of protein structure and function for experimental applications. For researchers conducting long-term studies, creating multiple small aliquots of the reconstituted protein is strongly recommended to minimize freeze-thaw cycles and maintain consistent experimental conditions .

What is the recommended reconstitution protocol for lyophilized UU265?

Proper reconstitution of lyophilized recombinant UU265 protein is essential for maintaining its structural and functional properties. The recommended protocol is:

• Preparation:

  • Allow the vial to equilibrate to room temperature

  • Briefly centrifuge to collect the lyophilized powder at the bottom of the tube

  • Work under sterile conditions to prevent contamination

• Reconstitution procedure:

  • Add deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL

  • Gently mix by swirling or light vortexing until completely dissolved

  • Avoid generating foam or bubbles that could denature the protein

  • Allow 5-10 minutes for complete rehydration

• Stabilization for storage:

  • For long-term storage, add glycerol to a final concentration of 5-50% (typically 50%)

  • Mix thoroughly but gently

  • Aliquot into smaller volumes to minimize future freeze-thaw cycles

• Quality assessment:

  • Visually inspect for complete dissolution

  • For critical applications, verify protein concentration using standard methods (Bradford, BCA, etc.)

This methodical approach ensures maximum protein activity and experimental reproducibility when working with UU265 in research settings.

What role does UU265 play in Ureaplasma parvum pathogenesis?

While the specific function of UU265 in Ureaplasma parvum pathogenesis is still being elucidated, several lines of evidence suggest potential roles:

• Membrane association: The protein's predicted transmembrane domains suggest it may function at the bacteria-host interface, potentially mediating adhesion or host cell interaction processes.

• Exosome interaction: Research demonstrates that U. parvum infection alters exosome biogenesis in host cells . As a membrane protein, UU265 may contribute to this process by:

  • Facilitating U. parvum's utilization of exosomes for propagation

  • Potentially incorporating into exosomal membranes

  • Modulating host cell membrane trafficking pathways

• Immune evasion: U. parvum can survive intracellularly and evade host immune responses . UU265 may participate in:

  • Intracellular survival mechanisms

  • Modulation of vesicular trafficking to avoid lysosomal degradation

  • Alteration of host cell signaling pathways

Evidence from proteomic studies shows that U. parvum infection affects multiple cellular pathways, including clathrin-mediated endocytosis and signaling cascades involved in infection, inflammation, and cell death processes . Understanding UU265's specific contribution to these pathogenic mechanisms requires further investigation using techniques such as gene knockout studies, protein-protein interaction assays, and localization studies during infection.

How does UU265 interact with host cellular pathways?

Based on research examining Ureaplasma parvum infection mechanisms, UU265 may interact with host cellular pathways in several significant ways:

• Vesicular trafficking pathways:

  • U. parvum infection alters proteins involved in endocytosis and exosome biogenesis

  • Specifically, infection decreases clathrin, ALIX, CD9, and CD63 while increasing TSG101, Rab5, Rab35, and UGCG

  • As a membrane protein, UU265 may directly interact with these pathways

• Signaling pathway modulation:

  • Proteomic studies indicate alterations in multiple signaling cascades, with GSK3β appearing as a central node in affected molecular networks

  • U. parvum infection affects Wnt/β-catenin signaling, with low-dose infection increasing β-catenin levels

  • Additional affected pathways include EIF2, integrin, mTOR, and RHO GTPases signaling

• Immune response interactions:

  • U. parvum can evade lysosomal degradation and autophagy

  • Infection disrupts normal inflammatory pathway components

Research has shown that U. parvum exhibits colonization of ectocervical epithelial cells and colocalization with CD9-positive intraluminal vesicles , suggesting potential roles for membrane proteins like UU265 in these processes. The differential protein profiles in exosomes derived from infected cells further indicate pathogen-induced alterations in vesicular trafficking and intercellular communication mechanisms .

What experimental approaches are optimal for studying UU265 function in vitro?

Multiple complementary approaches should be employed to comprehensively investigate UU265 function:

• Structural characterization:

  • X-ray crystallography or cryo-EM to determine three-dimensional structure

  • Circular dichroism spectroscopy for secondary structure assessment

  • Limited proteolysis to identify domain boundaries

• Protein-protein interaction studies:

  • Pull-down assays using His-tagged UU265 as bait

  • Surface plasmon resonance to measure binding kinetics

  • Proximity labeling techniques to identify interaction partners in cellular contexts

• Cellular localization:

  • Immunofluorescence using anti-UU265 antibodies in infected cells

  • Fractionation studies to determine membrane association

  • Co-localization with markers of specific cellular compartments (e.g., CD9 for exosomes)

• Functional assays:

  • Membrane binding/disruption assays

  • Host cell binding studies using purified protein

  • Exosome isolation and characterization from cells exposed to UU265

• Comparative analysis:

  • Site-directed mutagenesis to identify critical residues

  • Domain swapping with homologous proteins

This multi-faceted approach enables a comprehensive understanding of UU265's role in U. parvum biology and host-pathogen interactions, with particular attention to its potential involvement in altering exosome biogenesis and cellular signaling pathways.

How can UU265 be used to study U. parvum's effects on exosome biogenesis?

UU265 can serve as a valuable tool for investigating Ureaplasma parvum's impact on exosome biogenesis through several methodological approaches:

• Co-localization studies:

  • Immunocytochemical staining using U. parvum-specific markers (such as multiple banded antigen) together with exosome markers like CD9

  • Tracking UU265 localization relative to components of the endosomal-exosomal pathway

• Protein expression analysis:

  • Western blot analysis to examine how exposure to purified UU265 affects levels of key exosome biogenesis proteins:

    • ESCRT pathway components (TSG101, ALIX)

    • Tetraspanins (CD9, CD63)

    • Rab GTPases (Rab5, Rab35)

    • Other relevant proteins (UGCG, clathrin)

• Exosome isolation and characterization:

  • Comparison of exosomes from control cells versus cells exposed to UU265

  • NanoLC-MS/MS analysis to identify differentially expressed proteins in exosomes

  • Assessment of exosome number, size distribution, and morphology

• Pathway analysis:

  • Ingenuity Pathway Analysis (IPA) of proteomic data to identify affected canonical pathways and biological functions

  • Use of specific inhibitors to determine which pathways are directly affected by UU265

Research has already demonstrated that U. parvum infection alters exosome protein cargo and affects proteins involved in exosome biogenesis . Using purified UU265 protein allows researchers to determine whether this specific protein alone can recapitulate aspects of the full infection, providing mechanistic insights into how U. parvum manipulates host exosome pathways.

What challenges exist in studying the structure-function relationship of UU265?

Investigating the structure-function relationship of UU265 presents several significant challenges:

• Structural determination difficulties:

  • Membrane-associated proteins are notoriously difficult to crystallize

  • Small size (109 amino acids) may provide insufficient electron density for some techniques

  • Potential conformational dynamics may complicate structure determination

• Functional assay limitations:

  • Lack of known enzymatic activity makes traditional biochemical assays challenging

  • Difficulty establishing causality in complex host-pathogen interactions

  • Challenges in replicating the native membrane environment for in vitro studies

• Technical considerations:

  • Protein stability issues during purification and storage

  • Limited availability of specific antibodies for detection

  • Lack of established U. parvum genetic manipulation systems

These challenges necessitate a multidisciplinary approach combining structural biology, biochemistry, cell biology, and computational methods to fully understand the structure-function relationship of UU265 and its role in U. parvum pathogenesis.

How does UU265 affect host cell signaling pathways during infection?

Research on Ureaplasma parvum infection provides insights into how UU265 might influence host cell signaling:

• GSK3β/β-catenin pathway modulation:

  • GSK3β emerges as a central player in the molecular network of proteins affected during U. parvum infection

  • Low-dose U. parvum infection increases β-catenin levels without affecting GSK3β phosphorylation

  • High-dose infection significantly increases GSK3β phosphorylation without affecting β-catenin

  • These dose-dependent effects suggest nuanced regulation of this important signaling pathway

• Endocytic pathway alterations:

  • U. parvum infection disrupts clathrin-mediated endocytosis

  • The infection significantly decreases clathrin levels while increasing early endosome-associated proteins like Rab5

  • These changes may affect receptor signaling and membrane protein turnover

• Exosome-mediated signaling:

  • Proteomic analysis reveals distinct protein profiles in exosomes from infected cells

  • Altered exosome cargo affects intercellular communication

  • Changes in tetraspanins (CD9, CD63) may influence exosome targeting and uptake

• Inflammatory signaling:

  • Differentially expressed proteins are associated with infection, inflammation, and cell death processes

  • These changes may contribute to the pathophysiology of conditions like cervicitis and preterm birth

The specific contribution of UU265 to these signaling alterations requires further investigation, but as a membrane-associated protein with potential localization to host-pathogen interfaces, it may play a direct role in initiating or modulating these signaling events during infection.

What methods are effective for studying UU265 localization during infection?

Determining the precise localization of UU265 during infection requires a multi-faceted approach:

• Immunofluorescence microscopy:

  • Antibody-based detection of UU265 in infected cells

  • Co-staining with markers for:

    • U. parvum (e.g., multiple banded antigen)

    • Cellular compartments (early endosomes, late endosomes, MVBs)

    • Exosome markers (CD9, CD63)

  • Advanced techniques like confocal or super-resolution microscopy for precise localization

• Subcellular fractionation:

  • Separation of cellular compartments through differential centrifugation

  • Western blot analysis of fractions to detect UU265

  • Isolation of exosomes through ultracentrifugation or size exclusion chromatography

• Electron microscopy:

  • Immunogold labeling for ultrastructural localization

  • Transmission electron microscopy to visualize membrane associations

• Live cell imaging:

  • Tagged versions of UU265 (if function is preserved)

  • Real-time tracking of protein movement during infection

Research has already demonstrated that U. parvum colocalizes with CD9-positive intraluminal vesicles in infected cells , suggesting association with the exosomal pathway. Similar approaches can be applied to study UU265 specifically, providing insights into its subcellular distribution and potential functional sites during the infection process.

How does UU265 contribute to U. parvum's immune evasion strategies?

Evidence suggests UU265 may participate in Ureaplasma parvum's immune evasion mechanisms:

• Intracellular survival:

  • U. parvum can survive intracellularly and evade lysosomal degradation

  • As a membrane protein, UU265 may participate in:

    • Altering phagosome maturation

    • Interfering with phagolysosome fusion

    • Modifying intracellular trafficking pathways

• Endosomal-exosomal pathway manipulation:

  • U. parvum infection increases Rab5 (early endosome marker) and Rab35 (recycling endosome marker)

  • It affects Rab7 (late endosome/lysosome marker)

  • These alterations may prevent proper processing of the pathogen by the endolysosomal system

• Exosome exploitation:

  • U. parvum can utilize exosomes to propagate infection and its virulence factors

  • Modified exosome composition may affect immune recognition

  • Decreased exosomal protein abundance in infected cells suggests selective cargo sorting

• Signaling interference:

  • Altered GSK3β/β-catenin signaling may affect inflammatory responses

  • Disruption of clathrin-mediated endocytosis impacts receptor-mediated signaling

Research has shown that U. parvum infection significantly alters proteins involved in various stages of exosome biogenesis, including early endosome formation, cargo sorting, and multivesicular body formation . Understanding UU265's specific contribution to these processes could provide targets for novel therapeutic approaches to address Ureaplasma infections.

What are the methodological considerations for studying UU265 in different experimental models?

Effective study of UU265 across different experimental systems requires careful methodological planning:

• In vitro protein studies:

  • Recombinant protein production with appropriate tags (His-tag)

  • Protein purity >90% as determined by SDS-PAGE

  • Storage in Tris/PBS-based buffer with 6% Trehalose

  • Addition of glycerol (5-50%) for freeze protection

• Cell culture models:

  • Selection of relevant cell types (e.g., ectocervical epithelial cells)

  • Determination of appropriate infection doses

  • Time course studies to capture dynamic processes

  • Controls for non-specific effects

• Exosome studies:

  • Standardized isolation protocols (ultracentrifugation, size exclusion)

  • NanoLC-MS/MS analysis for protein identification

  • Western blot validation of key findings

  • Pathway analysis of proteomic data

• Functional assays:

  • Membrane interaction studies

  • Protein-protein interaction analyses

  • Signaling pathway activation measurement

  • Immune response assessment

• Comparative approaches:

  • Full-length vs. domain-specific constructs

  • Wild-type vs. mutant proteins

  • Comparison with homologous proteins from other Ureaplasma serovars

How can UU265 inform the development of novel therapeutic approaches?

Understanding UU265's structure and function could contribute to therapeutic development through several avenues:

• Targeting bacterial entry and survival:

  • If UU265 participates in clathrin-mediated endocytosis, as suggested by U. parvum infection studies , inhibiting this interaction could block bacterial entry

  • Compounds disrupting UU265's membrane association could compromise bacterial survival

  • Peptide-based inhibitors mimicking key UU265 domains might interfere with host-pathogen interactions

• Preventing exosome exploitation:

  • U. parvum utilizes exosomes to propagate infection

  • If UU265 contributes to this process, inhibitors could prevent:

    • Bacterial incorporation into exosomes

    • Alteration of exosome biogenesis

    • Exosome-mediated spread of infection

• Restoring normal cellular processes:

  • Counteracting UU265-induced changes in:

    • GSK3β/β-catenin signaling

    • Vesicular trafficking protein expression

    • Inflammatory pathway activation

• Vaccine development:

  • Evaluation of UU265 as a potential vaccine antigen

  • Assessment of protective immunity targeting this protein

  • Design of multi-component vaccines including UU265

Development of these approaches requires detailed understanding of UU265's molecular mechanisms and careful validation in relevant experimental models. Given U. parvum's association with reproductive pathologies like preterm birth and infertility , therapeutic strategies targeting this protein could have significant clinical impact in reproductive medicine.