PMID:24686057

Citation	Missineo, A, Di Poto, A, Geoghegan, JA, Rindi, S, Heilbronner, S, Gianotti, V, Arciola, CR, Foster, TJ, Speziale, P and Pietrocola, G' (2014) IsdC from Staphylococcus lugdunensis induces biofilm formation in low-iron growth conditions. Infect. Immun. '
Abstract	Staphylococcus lugdunensis is a coagulase-negative Staphylococcus that is a commensal of humans and an opportunistic pathogen. It can cause a spectrum of infections including those that are associated with the ability to form biofilm such as endocarditis or indwelling medical devices. The genome sequences of two strains revealed the presence of orthologues of the ica genes that are responsible for synthesis of poly-N-acetyl glucosamine (PNAG) that is commonly associated with biofilm in other staphylococci. However, here we discovered that biofilm formed by a panel of S. lugdunensis isolates growing in iron-restricted medium was susceptible to degradation by proteases and not by metaperiodate suggesting that the biofilm matrix comprised proteins and not PNAG. When the iron concentration was raised to 1mM biofilm formation by all strains tested was greatly reduced. A mutant of strain N920143 lacking the entire locus that encodes iron-regulated surface determinant (Isd) proteins was defective in biofilm formation under iron-limited conditions. A IsdC null mutant was defective whereas IsdK, IsdJ and IsdB mutants formed biofilm to the same level as the parental strain. Expression of IsdC was required both for the primary attachment to unconditioned polystyrene and for the accumulation phase of biofilm involving cell-cell interactions. Purified recombinant IsdC protein formed dimers in solution and Lactococcus lactis cells expressing only IsdC adhered to immobilized recombinant IsdC but not to IsdJ, IsdK or IsdB. This is consistent with a specific homophilic interaction between IsdC molecules on neighbouring cells contributing to accumulation of S. lugdunensis biofilm in vivo.
Links	PubMed Online version:10.1128/IAI.01542-14
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STALU:E6MC21		GO:0042710: biofilm formation	IMP: Inferred from Mutant Phenotype:	P	Figure 4 is able to demonstrate how one or more proteins expressed by the isd locus are involved in biofilm formation in iron deficient environments, due to the ability of the mutant with the isd locus deleted to produce the same amount of biofilm as the wild-type. The only mutant strand without the isd locus that shows growth on iron deficient media contains the IsdC protein. This illustrates the fact that IsdC is sufficient, all alone, in promoting biofilm formation in minimal iron conditions.	complete CACAO 10084
9STAP:A0A1F1MBJ8		GO:1900233: positive regulation of single-species biofilm formation on inanimate substrate	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Figure 4 first demonstrates how one or more proteins expressed by the isd locus are involved in biofilm formation in iron deficient environments, due to the ability of the mutant with the isd locus deleted to produce the same amount of biofilm as the wild-type. Furthermore in Figure 4, the isd mutant that lacked the entire isd locus bore an isdc gene engineered to express IsdC protein expression. Similar levels of biofilm formed in this mutant and the wild type. Therefore, IsdC is sufficient in promoting biofilm formation in low-iron environments all alone.	complete CACAO 10078

References

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