3gf8

Protein Summary

Bacteriodes thetaiotaomicron protein BT_1062 (target db id 393038) is a two domain, all-beta secreted protein which likely functions as a monomer. The structure of BT_1062 consists of  two beta sandwich domains with different, not readily alignable variants of the Greek key beta barrel topology. N-terminal domain has a prealbumin fold, found for instance in bacterial starch binding domain of beta-amylases (FATCAT alignment of an N-terminal domain of BT_1062 to the Starch-Binding Domain of Bacillus cereus B-amylase, PDB code 1cqy has an RMSD of 3.1 A with 15% sequence id). C-terminal domain has a topology similar to fibronectin III domain (FATCAT alignment to a second domain of the chain B of human interleukin 4 receptor, PDB code 1iar, has an RMSD of 3 A over 75 resiudes with a sequence id of 3.5%), but structural similarity to other sub-types of an immunoglobulin fold are also statistically significant.

Interestingly, as DUF1812 is distantly related to a family of Porphyromonas gingivalis major fimbrial subunit protein (FimA), PF06321, which are virulence factors involved in adhesion to and invasion of host (human) cells, structure and functional prediction for BT_1062 suggests a possible mechanism of function for these important virulence factors.

BT_1062 is a first representative of DUF1812 PF08842  family, large (close to 100 homologs) proteins specific to Bacteroides and present also in human gut metagenomic samples.

LipPred (cleavage residue: 25) and LipoP (sequence SpII score=7.50643 margin=3.35388 cleavage=24-25 Pos+2=D) predicts it as bacterial lipoprotein. Asp at position +2 in relation to amino-terminal Cys, indicates that this protein is probably attached to the cytoplasmic membrane at the periplasmic side.

Figure 1. monomer of 393038

Figure 2. the conserved residues are mainly located near the domain interface

39 VKFKYDYNMEFADAFHAQVDKVELYVFDKNGKYLFKQAEEGSALSTGNYLMEVELPVG-QYQFMAWAGARDSYDITSLTPGVSTLTDLKLKLKREASLII 137
 2 IIKSGEGRAVGDGLADAKITKLTAMVYAGQIQ---EGIKTVEEADGVLKVEGIPCKSGANRVLVVVANHNYELTGKSLNEVEALTTSLTAENQNAKNLIM 98

138 NKRMETL-------WYGEVINVNFDGTVHQTETINLIRDTKIVRFG-FQSYTGSWTLDMNDYDYE------IIESNGHLGHDNSLLDDDVLS-------- 215
 99 TGKSAAFTIKPGSNHYGYPDGTTSDNLVSAGTPLAVTRVHAGISFAGVEVNMATQYQNYYSFNPADAKIAALVAKKDSKIFGNSLVSNTNAYLYGVQTPA 198

215 ----------------------------FRPYYMEQKDPATAYVDMNTMRLMEDRKTRLVLTE-----------KASGKRVFDINLIDYLAMTNAEGKNL 276
199 GLYTPDAAGETYELEASLNTNYAVGAGFYVLESKYDASNELRPTILCIYGKLLDKDGNPLTEPALTDAINAGFCDGDGTTYYPVLVNYDGNGYIYSGAIT 298

277 STQEYLDRQSNYHIIFFLS-------------ESWLAVQIVVNGWVHRIQEE 315
299 QGQNKIVRNNHYKITLNITGPGTNTPENPQPVQANLNVTCQVTPWVVVNQAA 350