This domain is found in the virulence regulatory factor CvfB from Streptococcus pneumoniae and in similar proteins predominantly found in Firmicutes. CvfB is composed of three consecutive S1 RNA-binding domains and a winged-helix (WH) domain (Pfam:PF17783). This entry represents the second S! domain, an RNA-binding module that adopts the typical S1 fold that consists of a five-stranded, antiparallel beta-sheet forming a beta-barrel [1].

1: Structure of a virulence regulatory factor CvfB reveals a novel winged helix RNA binding module. Matsumoto Y, Xu Q, Miyazaki S, Kaito C, Farr CL, Axelrod HL, Chiu HJ, Klock HE, Knuth MW, Miller MD, Elsliger MA, Deacon AM, Godzik A, Lesley SA, Sekimizu K, Wilson IA; Structure. 2010;18:537-547. PMID:20399190