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Staphylococcus aureus is a gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains, such as methicillin-resistant S. aureus (MRSA). The bacterium is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.
Pathogenicity islands (PAIs), as termed in 1990, are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer. Pathogenicity islands are found in both animal and plant pathogens. Additionally, PAIs are found in both gram-positive and gram-negative bacteria. They are transferred through horizontal gene transfer events such as transfer by a plasmid, phage, or conjugative transposon. Therefore, PAIs contribute to microorganisms' ability to evolve.
The gene rpoS encodes the sigma factor sigma-38, a 37.8 kD protein in Escherichia coli. Sigma factors are proteins that regulate transcription in bacteria. Sigma factors can be activated in response to different environmental conditions. rpoS is transcribed in late exponential phase, and RpoS is the primary regulator of stationary phase genes. RpoS is a central regulator of the general stress response and operates in both a retroactive and a proactive manner: it not only allows the cell to survive environmental challenges, but it also prepares the cell for subsequent stresses (cross-protection). The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins, and the diguanylate cyclase, adrA, which indirectly activates cellulose production. The rpoS gene most likely originated in the gammaproteobacteria.
Panton–Valentine leukocidin (PVL) is a cytotoxin—one of the β-pore-forming toxins. The presence of PVL is associated with increased virulence of certain strains (isolates) of Staphylococcus aureus. It is present in the majority of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates studied and is the cause of necrotic lesions involving the skin or mucosa, including necrotic hemorrhagic pneumonia. PVL creates pores in the membranes of infected cells. PVL is produced from the genetic material of a bacteriophage that infects Staphylococcus aureus, making it more virulent.
The Hfq protein encoded by the hfq gene was discovered in 1968 as an Escherichia coli host factor that was essential for replication of the bacteriophage Qβ. It is now clear that Hfq is an abundant bacterial RNA binding protein which has many important physiological roles that are usually mediated by interacting with Hfq binding sRNA.
Toxic shock syndrome toxin-1 (TSST-1) is a superantigen with a size of 22 kDa produced by 5 to 25% of Staphylococcus aureus isolates. It causes toxic shock syndrome (TSS) by stimulating the release of large amounts of interleukin-1, interleukin-2 and tumor necrosis factor. In general, the toxin is not produced by bacteria growing in the blood; rather, it is produced at the local site of an infection, and then enters the blood stream.
Phenol-soluble modulins (PSMs) are a family of small proteins, that carry out a variety of functions, including acting as toxins, assisting in biofilm formation, and colony spreading. PSMs are produced by Staphylococcus bacteria including Methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus epidermidis. Many PSMs are encoded within the core genome and can play an important virulence factor. PSMs were first discovered in S. epidermidis by Seymour Klebanoff and via hot-phenol extraction and were described as a pro-inflammatory complex of three peptides. Since their initial discovery, numerous roles of PSMs have been identified. However, due in part to the small size of many PSMs, they have largely gone unnoticed until recent years.
In enzymology, a threonine-tRNA ligase is an enzyme that catalyzes the chemical reaction
60S ribosomal protein L7a is a protein that in humans is encoded by the RPL7A gene.
U1 small nuclear ribonucleoprotein A is a protein that in humans is encoded by the SNRPA gene.
'Staphylococcus aureus delta toxin is a toxin produced by Staphylococcus aureus. It has a wide spectrum of cytolytic activity.
Bacterial small RNAs are small RNAs produced by bacteria; they are 50- to 500-nucleotide non-coding RNA molecules, highly structured and containing several stem-loops. Numerous sRNAs have been identified using both computational analysis and laboratory-based techniques such as Northern blotting, microarrays and RNA-Seq in a number of bacterial species including Escherichia coli, the model pathogen Salmonella, the nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti, marine cyanobacteria, Francisella tularensis, Streptococcus pyogenes, the pathogen Staphylococcus aureus, and the plant pathogen Xanthomonas oryzae pathovar oryzae. Bacterial sRNAs affect how genes are expressed within bacterial cells via interaction with mRNA or protein, and thus can affect a variety of bacterial functions like metabolism, virulence, environmental stress response, and structure.
In molecular biology SprD is a non-coding RNA expressed on pathogenicity islands in Staphylococcus aureus. It was identified in silico along with a number of other sRNAs (SprA-G) through microarray analysis which were confirmed using a Northern blot. SprD has been found to significantly contribute to causing disease in an animal model.
Rsa RNAs are non-coding RNAs found in the bacterium Staphylococcus aureus. The shared name comes from their discovery, and does not imply homology. Bioinformatics scans identified the 16 Rsa RNA families named RsaA-K and RsaOA-OG. Others, RsaOH-OX, were found thanks to an RNomic approach. Although the RNAs showed varying expression patterns, many of the newly discovered RNAs were shown to be Hfq-independent and most carried a C-rich motif (UCCC).
SaPIs are a family of ~15 kb mobile genetic elements resident in the genomes of the vast majority of S. aureus strains. Much like bacteriophages, SaPIs can be transferred to uninfected cells and integrate into the host chromosome. Unlike the bacterial viruses, however, integrated SaPIs are mobilized by host infection with "helper" bacteriophages. SaPIs are used by the host bacteria to co-opt the phage reproduction cycle for their own genetic transduction and also inhibit phage reproduction in the process.
Glutamyl endopeptidase is an extracellular bacterial serine protease of the glutamyl endopeptidase I family that was initially isolated from the Staphylococcus aureus strain V8. The protease is, hence, commonly referred to as "V8 protease", or alternatively SspA from its corresponding gene.
Aureolysin is an extracellular metalloprotease expressed by Staphylococcus aureus. This protease is a major contributor to the bacterium's virulence, or ability to cause disease, by cleaving host factors of the innate immune system as well as regulating S. aureus secreted toxins and cell wall proteins. To catalyze its enzymatic activities, aureolysin requires zinc and calcium which it obtains from the extracellular environment within the host.
Staphopain A is a secreted cysteine protease produced by Staphylococcus aureus. It was first identified in the S. aureus V8 strain as a papain-like cysteine protease. The protease distinguishes itself from the other major proteases of S. aureus in its very broad specificity and its ability to degrade elastin.
Accessory gene regulator (agr) is a complex 5 gene locus that is a global regulator of virulence in Staphylococcus aureus. It encodes a two-component transcriptional quorum-sensing (QS) system activated by an autoinducing, thiolactone-containing cyclic peptide (AIP).
Richard P. Novick is an American microbiologist best known for his work in the fields of plasmid biology, staphylococcal pathobiology and antimicrobial resistance. He is the Recanati Family Professor of Science, Emeritus, at NYU Grossman School of Medicine and is a member of the American National Academy of Sciences. Novick has published over 250 peer-reviewed articles, and several book reviews for the Times Literary Supplement, and is a member of the Editorial Board of the Proceedings of the National Academy of Sciences.
References
- ↑ Novick RP, Ross HF, Projan SJ, Kornblum J, Kreiswirth B, Moghazeh S (October 1993). "Synthesis of staphylococcal virulence factors is controlled by a regulatory RNA molecule". The EMBO Journal. 12 (10): 3967–75. doi:10.1002/j.1460-2075.1993.tb06074.x. PMC 413679 . PMID 7691599.
- ↑ Waters LS, Storz G (February 2009). "Regulatory RNAs in bacteria". Cell. 136 (4): 615–28. doi:10.1016/j.cell.2009.01.043. PMC 3132550 . PMID 19239884.
- ↑ Janzon L, Arvidson S (May 1990). "The role of the delta-lysin gene (hld) in the regulation of virulence genes by the accessory gene regulator (agr) in Staphylococcus aureus". The EMBO Journal. 9 (5): 1391–9. doi:10.1002/j.1460-2075.1990.tb08254.x. PMC 551825 . PMID 2328718.
- ↑ Novick RP (June 2003). "Autoinduction and signal transduction in the regulation of staphylococcal virulence". Molecular Microbiology. 48 (6): 1429–49. doi: 10.1046/j.1365-2958.2003.03526.x . PMID 12791129. S2CID 6847208.
- 1 2 Benito Y, Kolb FA, Romby P, Lina G, Etienne J, Vandenesch F (May 2000). "Probing the structure of RNAIII, the Staphylococcus aureus agr regulatory RNA, and identification of the RNA domain involved in repression of protein A expression". RNA. 6 (5): 668–79. doi:10.1017/S1355838200992550. PMC 1369947 . PMID 10836788.
- ↑ Geisinger E, Adhikari RP, Jin R, Ross HF, Novick RP (August 2006). "Inhibition of rot translation by RNAIII, a key feature of agr function". Molecular Microbiology. 61 (4): 1038–48. doi: 10.1111/j.1365-2958.2006.05292.x . PMID 16879652. S2CID 229424.
- ↑ Boisset S, Geissmann T, Huntzinger E, Fechter P, Bendridi N, Possedko M, et al. (June 2007). "Staphylococcus aureus RNAIII coordinately represses the synthesis of virulence factors and the transcription regulator Rot by an antisense mechanism". Genes & Development. 21 (11): 1353–66. doi:10.1101/gad.423507. PMC 1877748 . PMID 17545468.
- ↑ Dunman PM, Murphy E, Haney S, Palacios D, Tucker-Kellogg G, Wu S, et al. (December 2001). "Transcription profiling-based identification of Staphylococcus aureus genes regulated by the agr and/or sarA loci". Journal of Bacteriology. 183 (24): 7341–53. doi:10.1128/JB.183.24.7341-7353.2001. PMC 95583 . PMID 11717293.
- ↑ Morfeldt E, Taylor D, von Gabain A, Arvidson S (September 1995). "Activation of alpha-toxin translation in Staphylococcus aureus by the trans-encoded antisense RNA, RNAIII". The EMBO Journal. 14 (18): 4569–77. doi:10.1002/j.1460-2075.1995.tb00136.x. PMC 394549 . PMID 7556100.
