Recombinant Rickettsia bellii Lipoprotein signal peptidase (lspA)
Description
Introduction to Recombinant Rickettsia bellii Lipoprotein Signal Peptidase (lspA)
Recombinant Rickettsia bellii Lipoprotein signal peptidase (lspA) is a genetically engineered form of the lspA enzyme, which is naturally produced by Rickettsia bellii, a species of bacteria within the genus Rickettsia. This enzyme plays a crucial role in the processing of lipoproteins, which are essential for bacterial cell membrane integrity and function. Lipoprotein signal peptidase II (SPase II) is responsible for cleaving the signal peptide from prolipoproteins, allowing them to mature into functional lipoproteins.
Function and Importance of lspA
The lspA gene encodes for the type II signal peptidase (SPase II), which is vital for the maturation of lipoproteins in gram-negative bacteria, including Rickettsia species. Lipoproteins are involved in various cellular processes, including cell wall maintenance, nutrient uptake, and virulence factor expression. The lspA enzyme ensures that these lipoproteins are properly processed and integrated into the bacterial membrane, which is critical for bacterial survival and pathogenicity.
Recombinant Expression and Applications
Recombinant expression of lspA from Rickettsia bellii allows for the production of this enzyme in large quantities, which can be used for various applications, including research into bacterial pathogenesis and the development of diagnostic tools. The recombinant enzyme can be used in ELISA assays to detect antibodies against Rickettsia bellii, aiding in the diagnosis of infections caused by this bacterium .
References
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Lipid modification of bacterial lipoproteins: The lspA gene from Rickettsia typhi encodes a type II signal peptidase involved in lipoprotein processing, which is critical for bacterial virulence and intracellular growth .
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Rickettsia bellii: This species is often considered non-pathogenic but has been implicated in some cases of human or animal disease, highlighting the need for further study .
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ELISA Kits: Recombinant Rickettsia bellii Lipoprotein signal peptidase (lspA) is used in ELISA kits for diagnostic purposes .
Product Specs
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Target Background
KEGG: rbo:A1I_02465
Q&A
FAQs for Researchers on Recombinant Rickettsia bellii Lipoprotein Signal Peptidase (LspA)
Advanced Research Questions
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How do contradictions in functional complementation assays inform SPase II activity?
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Key Findings:
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Resolution Strategy:
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Perform structural modeling to compare active sites (e.g., conserved Ser/Lys residues).
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Test hybrid proteins or site-directed mutants to isolate functional domains.
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What methodologies resolve challenges in lipoprotein vs. nonlipoprotein secretion in Rickettsia?
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Integrated Approach:
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Bioinformatic Prediction: Use SignalP/LipoP to classify secretory proteins. In R. typhi, 89 secretory proteins were predicted, with only 14 as lipoproteins .
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Expression Correlation: Compare lspA (lipoprotein processing) and lepB (nonlipoprotein SPase I) transcription. lepB showed 2–3× higher expression, implying broader substrate range .
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Data Tables
Table 1: Transcriptional Kinetics of lspA, lgt, and lepB in R. typhi
| Gene | Preinfection | 8 hpi | 48 hpi | 120 hpi |
|---|---|---|---|---|
| lspA | 100% | 40% | 220% | 60% |
| lgt | 95% | 38% | 210% | 58% |
| lepB | 150% | 70% | 300% | 80% |
| Data normalized to preinfection levels . |
Table 2: Functional Complementation of E. coli Y815
| LspA Source | Growth Restoration at 42°C | Globomycin Resistance (μg/ml) |
|---|---|---|
| E. coli | 100% | 200 |
| R. typhi | 20% | 200 |
| Growth restoration relative to wild-type E. coli . |
Methodological Recommendations
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Primer Design for lspA: Use conserved regions from alignment (e.g., Ser-39, Lys-83 in R. typhi) .
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Heterologous Expression: Optimize induction conditions (e.g., IPTG concentration) to avoid toxicity from SPase II overexpression .
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Contradiction Analysis: Pair genetic complementation with proteomic profiling to identify unprocessed substrates.
