Recombinant Nicotiana tabacum 40S ribosomal protein S9 (RPS9)

What is the structural composition of Nicotiana tabacum RPS9?

Nicotiana tabacum RPS9 is a component of the 40S ribosomal subunit that functions in protein synthesis. The recombinant form available for research typically consists of amino acids 1-77 with the sequence: AKSVHHARVL IRQRHIRVGR QVVNVPSFMV RLDSQKHIDF SLISPFGGGR PGRVKRKNQK AAAKKASGGD GDEEDEE . The protein belongs to the S4P family of ribosomal proteins and is typically located in the cytoplasm where it participates in translation processes . When expressed recombinantly, it is commonly conjugated with a histidine tag (His-tag) to facilitate purification and detection in experimental settings .

How does RPS9 function within the ribosomal complex of Nicotiana tabacum?

RPS9 serves as a critical component of the small 40S ribosomal subunit in Nicotiana tabacum. Ribosomes, which catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit that together comprise 4 RNA species and approximately 80 structurally distinct proteins . Within this complex, RPS9 plays a role in maintaining ribosomal structure and facilitating the translation process. The protein's positioning within the ribosome and its RNA-binding motifs suggest it participates in mRNA-ribosome interactions during protein synthesis, contributing to translational fidelity and efficiency in tobacco cells.

What expression systems are commonly used for producing recombinant Nicotiana tabacum RPS9?

The yeast protein expression system is predominantly used for recombinant Nicotiana tabacum RPS9 production, as it represents the most economical and efficient eukaryotic system for both secretion and intracellular expression of plant proteins . This system provides proper folding and post-translational modifications that are important for maintaining the protein's functional characteristics. Alternative expression systems include E. coli, mammalian cells, or baculovirus infection systems, each with different implications for protein quality, yield, price, and lead time . For researchers seeking specific experimental applications, the choice between these expression systems should be guided by the requirements for protein authenticity and downstream applications.

What are the validated research applications for recombinant Nicotiana tabacum RPS9?

Recombinant Nicotiana tabacum RPS9 with His-tag has been validated primarily for ELISA applications . The high purity (>90%) of commercially available recombinant RPS9 makes it suitable for immunological detection methods. For human RPS9 variants, the applications extend to SDS-PAGE, Western Blotting, immunogen preparation, and as positive controls in various experimental setups . Researchers can leverage this protein for studying ribosome assembly, translation mechanisms, and as a marker in stress response studies in plants, particularly within the Solanaceae family. The protein's defined sequence and tag make it valuable for generating antibodies against native RPS9 or for comparative structural studies across species.

How can recombinant RPS9 be used in transcriptomic studies of Nicotiana tabacum?

Recombinant RPS9 can serve as a valuable tool in transcriptomic studies of Nicotiana tabacum, particularly when investigating responses to various treatments or stressors. As demonstrated in research with bacterial cold-shock proteins, RPS9 expression patterns can be analyzed as part of broader transcriptomic profiles . Methodologically, researchers can use the recombinant protein as a standard or control when quantifying native RPS9 expression levels in different experimental conditions. Additionally, antibodies raised against the recombinant protein can facilitate immunoprecipitation of RPS9-associated RNA complexes, enabling the identification of mRNAs interacting with this ribosomal protein during stress responses or developmental stages in tobacco plants.

What buffer conditions and storage parameters optimize recombinant RPS9 stability?

For optimal stability of recombinant RPS9 proteins, they are typically provided in lyophilized form and should be reconstituted in PBS buffer at pH 7.4 containing preservation agents such as 0.01% SKL, 1 mM DTT, 5% Trehalose, and ProClin300 . Once reconstituted, the protein should be stored at -20°C for medium-term storage or -80°C for long-term preservation, with aliquoting recommended to avoid repeated freeze-thaw cycles. For experiments requiring native-like conditions, buffer systems that mimic cytoplasmic conditions (pH 7.2-7.4 with physiological salt concentrations) are advisable. Researchers should note that ProClin is classified as hazardous and should be handled appropriately in laboratory settings .

How does RPS9 expression change during stress responses in Nicotiana tabacum?

While the search results don't directly address RPS9 expression changes during stress in Nicotiana tabacum, transcriptomic studies of tobacco plants treated with bacterial cold-shock proteins provide relevant insights into how ribosomal proteins may respond to stress conditions . In plants, ribosomal proteins often show altered expression patterns during various stress responses as part of the cellular adaptation mechanism. These changes can reflect adjustments in translational machinery to prioritize synthesis of stress-response proteins. To study such changes, researchers typically employ qRT-PCR to quantify RPS9 transcript levels across different stress conditions and time points, or use RNA-seq approaches for genome-wide expression profiling that includes ribosomal proteins. Western blotting with anti-RPS9 antibodies can provide protein-level confirmation of expression changes.

What is the relationship between RPS9 and nonspecific resistance pathways in tobacco?

The relationship between RPS9 and nonspecific resistance pathways in tobacco is complex and can be studied in the context of broader transcriptomic responses. Research on tobacco plants treated with bacterial cold-shock proteins has shown activation of both Systemic Acquired Resistance (SAR) and Induced Systemic Resistance (ISR) pathways, with differential expression of marker genes including PR1a (for SAR) and PDF1.2, PR4 (for ISR) . Ribosomal proteins, including RPS9, may be regulated as part of these immune responses, potentially contributing to translational reprogramming during pathogen defense. Methodologically, researchers can investigate this relationship by monitoring RPS9 expression alongside established SAR/ISR markers in response to various elicitors or pathogens, potentially revealing correlations between ribosomal protein expression and immune pathway activation.

How does Nicotiana tabacum RPS9 compare structurally and functionally with RPS9 proteins from other species?

Comparative analysis of RPS9 proteins across species reveals both conserved and variable regions that reflect evolutionary adaptations. The table below summarizes key comparative features of RPS9 from different organisms based on the available search results:

The functional conservation of RPS9 across species suggests its fundamental role in translation is maintained, while differences in protein length and sequence may reflect species-specific adaptations in translational regulation or extraribosomal functions. Researchers can leverage these comparative insights when designing cross-species experiments or when selecting appropriate model systems for studying RPS9 functions.

What approaches can be used to study protein-protein interactions involving RPS9 in tobacco?

To study protein-protein interactions involving RPS9 in tobacco, researchers can employ several complementary approaches. Co-immunoprecipitation (Co-IP) using antibodies against recombinant RPS9 can pull down native interaction partners from tobacco cell lysates, followed by mass spectrometry identification. Yeast two-hybrid screening using RPS9 as bait can identify direct interactors, while bimolecular fluorescence complementation (BiFC) can validate these interactions in planta. For capturing dynamic interactions within the ribosome, chemical cross-linking followed by mass spectrometry (XL-MS) can map spatial relationships between RPS9 and neighboring proteins. Proximity-dependent biotin identification (BioID) or APEX2 proximity labeling, where RPS9 is fused to a biotin ligase, can identify proximal proteins in living cells. These methodological approaches provide complementary data on RPS9's interaction network in tobacco cells.

How can CRISPR-Cas9 technology be utilized to study RPS9 function in Nicotiana tabacum?

CRISPR-Cas9 technology offers powerful approaches for studying RPS9 function in Nicotiana tabacum through targeted genetic modifications. Since complete knockout of essential ribosomal proteins is often lethal, researchers should consider alternative strategies: (1) Creating conditional knockdowns using inducible promoters driving Cas9 or RNAi constructs; (2) Introducing specific point mutations to alter functional domains without eliminating the protein entirely; (3) Adding epitope tags or fluorescent protein fusions to the endogenous RPS9 locus for tracking expression and localization; or (4) Modifying RPS9 promoter regions to study transcriptional regulation. For implementation, researchers should design guide RNAs targeting specific RPS9 regions, transform tobacco cells using Agrobacterium-mediated methods, screen transformants using PCR and sequencing, and validate modifications through expression analysis and phenotypic characterization.

What methodologies are appropriate for studying RPS9 involvement in translational regulation during tobacco stress responses?

To study RPS9's role in translational regulation during tobacco stress responses, researchers should employ a multi-faceted approach combining several specialized techniques. Polysome profiling, which separates actively translating ribosomes on sucrose gradients, can reveal stress-induced changes in global translation, with RPS9 distribution monitored by western blotting across fractions. Ribosome profiling (Ribo-seq) provides genome-wide snapshots of ribosome positions on mRNAs, allowing identification of transcripts whose translation is particularly affected by stress. RNA immunoprecipitation (RIP) using anti-RPS9 antibodies can identify mRNAs preferentially associated with RPS9-containing ribosomes during stress. Complementary transcriptomic and proteomic analyses can distinguish translational from transcriptional regulation. Additionally, in vitro translation systems reconstituted with or without recombinant RPS9 can test its direct effect on the translation of specific stress-response mRNAs. Together, these methodologies provide comprehensive insights into how RPS9 contributes to translational reprogramming during tobacco stress responses.

What are the current limitations in RPS9 research and future perspectives?

Current limitations in Nicotiana tabacum RPS9 research include incomplete characterization of its extraribosomal functions, limited understanding of post-translational modifications affecting its activity, and insufficient data on how it might participate in specialized ribosomes during stress responses. The partial protein sequence (AA 1-77) available as recombinant protein represents only a portion of the full-length RPS9, potentially limiting functional studies. Future research should focus on comprehensive structural determination of tobacco RPS9, identification of its complete interactome in different cellular conditions, and investigation of potential specialized functions in different tissues or developmental stages. The emergence of cryo-EM techniques for ribosome structure determination and advanced proteomics approaches offer promising avenues to address these knowledge gaps and expand our understanding of this important ribosomal protein in plant biology.