References

Project:

Staphylococcus aureus MW2

About this genome

Genome and virulence determinants of high virulence community-acquired MRSA.
Baba T.,Takeuchi F.,Kuroda M.,Yuzawa H.,Aoki K.,Oguchi A.,Nagai Y.,Iwama N.,Asano K.,Naimi T.,Kuroda H.,Cui L.,Yamamoto K.,Hiramatsu K. Lancet 359 (2002) 1819-27 [PMID: 12044378] Abstract
Abstract: BACKGROUND: A new type of meticillin-resistant Staphylococcus aureus (MRSA), designated community-acquired MRSA, is becoming increasingly noticeable in the community, some strains of which cause fatal infections in otherwise healthy individuals. By contrast with hospital-acquired MRSA, community-acquired MRSA is more susceptible to non b-lactam antibiotics. We investigated the high virulence potential of certain strains of this bacterium. METHODS: We ascertained the whole genome sequence of MW2, a strain of community-acquired MRSA, by shotgun cloning and sequencing. MW2 caused fatal septicaemia and septic arthritis in a 16-month-old girl in North Dakota, USA, in 1998. The genome of this strain was compared with those of hospital-acquired MRSA strains, including N315 and Mu50. FINDINGS: Meticillin resistance gene (mecA) in MW2 was carried by a novel allelic form (type IVa) of staphylococcal cassette chromosome mec (SCCmec), by contrast with type II in N315 and Mu50. Type IVa SCCmec did not carry any of the multiple antibiotic resistance genes reported in type II SCCmec. By contrast, 19 additional virulence genes were recorded in the MW2 genome. All but two of these virulence genes were noted in four of the seven genomic islands of MW2. INTERPRETATION: MW2 carried a range of virulence and resistance genes that was distinct from those displayed on the chromosomes of extant S aureus strains. Most genes were carried by specific allelic forms of genomic islands in the MW2 chromosome. The combination of allelic forms of genomic islands is the genetic basis that determines the pathogenicity of medically important phenotypes of S aureus, including those of community-acquired MRSA strains.

Genome and virulence determinants of high virulence community-acquired MRSA.

Baba T.,Takeuchi F.,Kuroda M.,Yuzawa H.,Aoki K.,Oguchi A.,Nagai Y.,Iwama N.,Asano K.,Naimi T.,Kuroda H.,Cui L.,Yamamoto K.,Hiramatsu K.
Lancet 359 (2002) 1819-27 [PMID: 12044378] Abstract

Journal

*Requirement of Staphylococcus aureus* ATP-binding cassette-ATPase FhuC for iron-restricted growth and evidence that it functions with more than one iron transporter.**
Speziali CD.,Dale SE.,Henderson JA.,Vines ED.,Heinrichs DE. J. Bacteriol. 188 (2006) 2048-55 [PMID: 16513734] Abstract
Abstract: In Staphylococcus aureus, fhuCBG encodes an ATP-binding cassette (ABC) transporter that is required for the transport of iron(III)-hydroxamates; mutation of either fhuB or fhuG eliminates transport. In this paper, we describe construction and characterization of an S. aureus fhuCBG deletion strain. The delta fhuCBG::ermC mutation not only resulted in a strain that was incapable of growth on iron(III)-hydroxamates as a sole source of iron but also resulted in a strain which had a profound growth defect in iron-restricted laboratory media. The growth defect was not a result of the inability to transport iron(III)-hydroxamates since S. aureus fhuG::Tn917 and S. aureus fhuD1::Km fhuD2::Tet mutants, which are also unable to transport iron(III)-hydroxamates, do not have similar iron-restricted growth defects. Complementation experiments demonstrated that the growth defect of the delta fhuCBG::ermC mutant was the result of the inability to express FhuC and that this was the result of an inability to transport iron complexed to the S. aureus siderophore staphylobactin. Transport of iron(III)-staphylobactin is dependent upon SirA (binding protein), SirB (permease), and SirC (permease). S. aureus expressing FhuC with a Walker A K42N mutation could not utilize iron(III)-hydroxamates or iron(III)-staphylobactin as a sole source of iron, supporting the conclusion that FhuC, as expected, functions with FhuB, FhuG, and FhuD1 or FhuD2 to transport iron(III)-hydroxamates and is the "genetically unlinked" ABC-ATPase that functions with SirA, SirB, and SirC to transport iron(III)-staphylobactin. Finally, we demonstrated that the delta fhuCBG::ermC strain had decreased virulence in a murine kidney abscess model.
*Role of siderophore biosynthesis in virulence of Staphylococcus aureus: identification and characterization of genes involved in production of a siderophore.*
Dale SE.,Doherty-Kirby A.,Lajoie G.,Heinrichs DE. Infect. Immun. 72 (2004) 29-37 [PMID: 14688077] Abstract
Abstract: Molecular determinants underlying the production of siderophores in the human and animal pathogen Staphylococcus aureus and the contribution of siderophore production to the virulence of this bacterium have, until now, remained undefined. Here, we show that S. aureus strains RN6390 and Newman produce siderophore when the cells are starved for iron. We further identified and characterized a nine-gene, iron-regulated operon, designated sbn and situated between sirABC and galE on the S. aureus chromosome, that is involved in the production of a siderophore. Mutation of the sbnE gene, in both RN6390 and Newman, eliminates the ability of these strains to produce a siderophore under iron-limited growth conditions, while introduction of multicopy sbnE into sbnE mutants complemented the inability of the mutants to produce the siderophore. sbnE mutants, in both the RN6390 and Newman backgrounds, displayed a drastic growth deficiency, compared to the wild type, in iron-restricted growth medium, whereas no such deficiency was observed during growth in iron-replete medium. Complemented mutants showed a restored ability to grow under iron restriction. We further showed that an sbnE mutant was compromised in a murine kidney abscess model of S. aureus infection, illustrating the importance of siderophore production to the pathogenicity of S. aureus. sbn genes were present in all S. aureus strains tested (and all S. aureus genome sequences) but were undetectable in any of the 13 coagulase-negative staphylococci tested, including Staphylococcus epidermidis.
*Identification and characterization of fhuD1 and fhuD2, two genes involved in iron-hydroxamate uptake in Staphylococcus aureus.*
Sebulsky MT.,Heinrichs DE. J. Bacteriol. 183 (2001) 4994-5000 [PMID: 11489851] Abstract
Abstract: Staphylococcus aureus can utilize several hydroxamate siderophores for growth under iron-restricted conditions. Previous findings have shown that S. aureus possesses a cytoplasmic membrane-associated traffic ATPase that is involved in the specific transport of iron(III)-hydroxamate complexes. In this study, we have identified two additional genes, termed fhuD1 and fhuD2, whose products are involved in this transport process in S. aureus. We have shown that fhuD2 codes for a posttranslationally modified lipoprotein that is anchored in the cytoplasmic membrane, while the deduced amino acid sequence predicts the same for fhuD1. The predicted FhuD1 and FhuD2 proteins share 41.0% identity and 56.4% total similarity with each other, 45.9 and 49.1% total similarity with the FhuD homolog in Bacillus subtilis, and 29.3 and 24.6% total similarity with the periplasmic FhuD protein from Escherichia coli. Insertional inactivation and gene replacement of both genes showed that while FhuD2 is involved in the transport of iron(III) in complex with ferrichrome, ferrioxamine B, aerobactin, and coprogen, FhuD1 shows a more limited substrate range, capable of only iron(III)-ferrichrome and iron(III)-ferrioxamine B transport in S. aureus. Nucleotide sequences present upstream of both fhuD1 and fhuD2 predict the presence of consensus Fur binding sequences. In agreement, transcription of both genes was negatively regulated by exogenous iron levels through the activity of the S. aureus Fur protein.
Identification and characterization of a membrane permease involved in iron-hydroxamate transport in Staphylococcus aureus.
Sebulsky MT.,Hohnstein D.,Hunter MD.,Heinrichs DE. J. Bacteriol. 182 (2000) 4394-400 [PMID: 10913070] Abstract
Abstract: Staphylococcus aureus was shown to transport iron complexed to a variety of hydroxamate type siderophores, including ferrichrome, aerobactin, and desferrioxamine. An S. aureus mutant defective in the ability to transport ferric hydroxamate complexes was isolated from a Tn917-LTV1 transposon insertion library after selection on iron-limited media containing aerobactin and streptonigrin. Chromosomal DNA flanking the Tn917-LTV1 insertion was identified by sequencing of chromosomal DNA isolated from the mutant. This information localized the transposon insertion to a gene whose predicted product shares significant similarity with FhuG of Bacillus subtilis. DNA sequence information was then used to clone a larger fragment of DNA surrounding the fhuG gene, and this resulted in the identification of an operon of three genes, fhuCBG, all of which show significant similarities to ferric hydroxamate uptake (fhu) genes in B. subtilis. FhuB and FhuG are highly hydrophobic, suggesting that they are embedded within the cytoplasmic membrane, while FhuC shares significant homology with ATP-binding proteins. Given this, the S. aureus FhuCBG proteins were predicted to be part of a binding protein-dependent transport system for ferric hydroxamates. Exogenous iron levels were shown to regulate ferric hydroxamate uptake in S. aureus. This regulation is attributable to Fur in S. aureus because a strain containing an insertionally inactivated fur gene showed maximal levels of ferric hydroxamate uptake even when the cells were grown under iron-replete conditions. By using the Fur titration assay, it was shown that the Fur box sequences upstream of fhuCBG are recognized by the Escherichia coli Fur protein.