Streptococcus is a genus of gram-positive coccus or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Bacillota. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.
Streptococcus pyogenes is a species of Gram-positive, aerotolerant bacteria in the genus Streptococcus. These bacteria are extracellular, and made up of non-motile and non-sporing cocci that tend to link in chains. They are clinically important for humans, as they are an infrequent, but usually pathogenic, part of the skin microbiota that can cause Group A streptococcal infection. S. pyogenes is the predominant species harboring the Lancefield group A antigen, and is often called group A Streptococcus (GAS). However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen as well. Group A streptococci, when grown on blood agar, typically produce small (2–3 mm) zones of beta-hemolysis, a complete destruction of red blood cells. The name group A (beta-hemolytic) Streptococcus (GABHS) is thus also used.
fis is an E. coli gene encoding the Fis protein. The regulation of this gene is more complex than most other genes in the E. coli genome, as Fis is an important protein which regulates expression of other genes. It is supposed that fis is regulated by H-NS, IHF and CRP. It also regulates its own expression (autoregulation). Fis is one of the most abundant DNA binding proteins in Escherichia coli under nutrient-rich growth conditions.
RNAIII is a stable 514 nt regulatory RNA transcribed by the P3 promoter of the Staphylococcus aureus quorum-sensing agr system ). It is the major effector of the agr regulon, which controls the expression of many S. aureus genes encoding exoproteins and cell wall associated proteins plus others encoding regulatory proteins The RNAIII transcript also encodes the 26 amino acid δ-haemolysin peptide (Hld). RNAIII contains many stem loops, most of which match the Shine-Dalgarno sequence involved in translation initiation of the regulated genes. Some of these interactions are inhibitory, others stimulatory; among the former is the regulatory protein Rot. In vitro, RNAIII is expressed post exponentially, inhibiting translation of the surface proteins, notably protein A, while stimulating that of the exoproteins, many of which are tissue-degrading enzymes or cytolysins. Among the latter is the important virulence factor, α-hemolysin (Hla), whose translation RNAIII activates by preventing the formation of an inhibitory foldback loop in the hla mRNA leader.
In molecular biology the ArcZ RNA is a small non-coding RNA (ncRNA). It is the functional product of a gene which is not translated into protein. ArcZ is an Hfq binding RNA that functions as an antisense regulator of a number of protein coding genes.
Invasion gene associated RNA is a small non-coding RNA involved in regulating one of the major outer cell membrane porin proteins in Salmonella species.
An Hfq binding sRNA is an sRNA that binds the bacterial RNA binding protein called Hfq. A number of bacterial small RNAs which have been shown to bind to Hfq have been characterised . Many of these RNAs share a similar structure composed of three stem-loops. Several studies have expanded this list, and experimentally validated a total of 64 Hfq binding sRNA in Salmonella Typhimurium. A transcriptome wide study on Hfq binding sites in Salmonella mapped 126 Hfq binding sites within sRNAs. Genomic SELEX has been used to show that Hfq binding RNAs are enriched in the sequence motif 5′-AAYAAYAA-3′. Genome-wide study identified 40 candidate Hfq-dependent sRNAs in plant pathogen Erwinia amylovora. 12 of them were confirmed by Northern blot.
The asd RNA motif is a conserved RNA structure found in certain lactic acid bacteria. The asd motif was detected by bioinformatics and an individual asd RNA in Streptococcus pyogenes was detected by microarray and northern hybridization experiments as a 170-nucleotide molecule called "SR914400". The transcription start site determined for SR914400 corresponds to the 5′-end of the molecule shown in the consensus diagram.
FourU thermometers are a class of non-coding RNA thermometers found in Salmonella. They are named 'FourU' due to the four highly conserved uridine nucleotides found directly opposite the Shine-Dalgarno sequence on hairpin II (pictured). RNA thermometers such as FourU control regulation of temperature via heat shock proteins in many prokaryotes. FourU thermometers are relatively small RNA molecules, only 57 nucleotides in length, and have a simple two-hairpin structure.
Bacterial small RNAs (bsRNA) 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.
Mga is a DNA-binding protein that activates the expression of several important virulence genes in Streptococcus pyogenes in response to changing environmental conditions. The family also contains VirR like proteins which match only at the C-terminus.
In molecular biology, the ferric uptake regulator family is a family of bacterial proteins involved in regulating metal ion uptake and in metal homeostasis. The family is named for its founding member, known as the ferric uptake regulator or ferric uptake regulatory protein (Fur). Fur proteins are responsible for controlling the intracellular concentration of iron in many bacteria. Iron is essential for most organisms, but its concentration must be carefully managed over a wide range of environmental conditions; high concentrations can be toxic due to the formation of reactive oxygen species.
In molecular biology, cia-dependent small RNAs (csRNAs) are small RNAs produced by Streptococci. These RNAs are part of the regulon of the CiaRH two-component regulatory system. Two of these RNAs, csRNA4 and csRNA5, have been shown to affect stationary-phase autolysis.
In molecular biology, the FasX small RNA (fibronectin/fibrinogen-binding/haemolytic-activity/streptokinase-regulator-X) is a non-coding small RNA (sRNA) produced by all group A Streptococcus. FasX has also been found in species of group D and group G Streptococcus. FasX regulates expression of secreted virulence factor streptokinase (SKA), encoded by the ska gene. FasX base pairs to the 5' end of the ska mRNA, increasing the stability of the mRNA, resulting in elevated levels of streptokinase expression. FasX negatively regulates the expression of pili and fibronectin-binding proteins on the bacterial cell surface. It binds to the 5' untranslated region of genes in the FCT-region in a serotype-specific manner, reducing the stability of and inhibiting translation of the pilus biosynthesis operon mRNA by occluding the ribosome-binding site through a simple Watson-Crick base-pairing mechanism.
In molecular biology, VR-RNA is a small RNA produced by Clostridium perfringens. It functions as a regulator of the two-component VirR/VirS system.
In molecular biology, Streptococcus sRNAs are small RNAs produced by species of Streptococcus bacteria. Several screens have identified numerous sRNAs in different species and strains of Streptococcus including S. pneumoniae, S. pyogenes, S. agalactiae and S.mutans. The function of most of these is currently unknown, however a few have been characterised including FasX small RNA. Many sRNAs have roles in pathogenesis.
In molecular biology, Vibrio cholerae ToxT activated RNAs are small RNAs which are produced by the bacterium Vibrio cholerae. They are regulated by the transcriptional activator ToxT and may play a role in V. cholerae virulence. Two ToxT activated RNAs have been described: TarA and TarB.
The gene rpoN encodes the sigma factor sigma-54, a protein in Escherichia coli and other species of bacteria. RpoN antagonizes RpoS sigma factors.
The locus of enterocyte effacement-encoded regulator (Ler) is a regulatory protein that controls bacterial pathogenicity of enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic Escherichia coli (EHEC). More specifically, Ler regulates the locus of enterocyte effacement (LEE) pathogenicity island genes, which are responsible for creating intestinal attachment and effacing lesions and subsequent diarrhea: LEE1, LEE2, and LEE3. LEE1, 2, and 3 carry the information necessary for a type III secretion system. The transcript encoding the Ler protein is the open reading frame 1 on the LEE1 operon.
RopB transcriptional regulator, also known as RopB/Rgg transcriptional regulator is a transcriptional regulator protein that regulates expression of the extracellularly secreted cysteine protease streptococcal pyrogenic exotoxin B (speB) [See Also: erythrogenic toxins] which is an important virulence factor of Streptococcus pyogenes and is responsible for the dissemination of a host of infectious diseases including strep throat, impetigo, streptococcal toxic shock syndrome, necrotizing fasciitis, and scarlet fever. Functional studies suggest that the ropB multigene regulon is responsible for not only global regulation of virulence but also a wide range of functions from stress response, metabolic function, and two-component signaling. Structural studies implicate ropB's regulatory action being reliant on a complex interaction involving quorum sensing with the leaderless peptide signal speB-inducing peptide (SIP) acting in conjunction with a pH sensitive histidine switch.
