Identification, expression and chromosome localization of a human gene encoding a novel protein with similarity to the pilB family of transcriptionalfactors (pilin) and to bacterial peptide methionine sulfoxide reductases

Here we report the isolation, characterization and chromosome localization of a subtracted cDNA (CBS-1) isolated from the human ocular ciliary body wh ich encodes a novel protein. As is deduced from the nucleotide sequence of the cDNA, CBS-1 contains an open reading frame consisting of 182 amino acid s, with a molecular weight of 19.5 kDa. CBS-1 shares significant nucleotide and amino acid sequence identities (residues 51 to 182) with a hypothetica l 15.5 kDa protein in the ANSA-GAP intergenic region (yeaA) of Escherichia coil, and the carboxyl terminal region of pilB, a transcription factor invo lved in the regulation of expression of pill, from Neisseria gonorrhoeae. I nterestingly, CBS-1 also shares significant identity with the carboxyl term inus of the peptide-methionine sulfoxide reductase (MsrA), a repair enzyme, from Helicobacter pylori and Streptococcus pneumoniae. However, the amino terminal of CBS-I (residues 23 to 43), which lacks homology to the amino te rminal region of gonococcal pilB or pneumococcal MsrA, exhibits significant identity in a stretch of 20 amino acids, with glycine-rich proteins. By No rthern blot, CBS-1, hybridized to a 0.6 to 0.7 kb transcript in size, is ex pressed ubiquitously in many tissues, but most abundantly in the retina and ocular ciliary body, skeletal muscle and heart. An epitope-directed antibo dy to an amino acid sequence at the carboxyl terminus of CBS-1 recognized a main protein of 19.5 kDa in ocular ciliary body extracts, and a 23 kDa pro tein in total extracts from E. coil MC1061 cells, which expresses high leve ls of MsrA. The CBS-1 gene was mapped to human chromosome 10p12 between mar kers WI-8535 and WI-4724, and is tightly linked to the two STRP markers of D10S1789 and D10S550. We suggest that the CBS-1 gene encodes a mammalian tr anscription factor related to the bacterial pilB and certain bacterial MsrA homologues. (C) 1999 Elsevier Science B.V. All rights reserved.