In molecular biology SprD (Small pathogenicity island RNA D) 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.
Function.
SprD is located between genes "scn" and "chp" in the innate immune evasion cluster (IEC) of the "S. aureus" genome. Its placement within this region was the first indication of a virulence-factor regulatory function.
SprD binds with "sbi" ("Staphylococcus aureus" binder of IgG) mRNA which encodes an immune evasion protein. It occludes the Shine-Dalgarno sequence and the initiation codon of "sbi", forming a "sbi" mRNA-SprD duplex repressing the translation of the mRNA.
"sbi" protein interferes with the host's innate immune response by binding Factor H, Complement component 3 and IgG.
References.
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Further reading.
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