Abstract

ShdA from Salmonella Typhimurium (ShdA(STm)) is a large outer membrane protein that specifically recognizes and binds to fibronectin. ShdA(STm) is involved in the colonization of the cecum and the Peyer's patches of terminal ileum in mice. On the other hand, shdA gene from Salmonella Typhi (shdA(STy)) has been considered a pseudogene (i. e. a nonfunctional sequence of genomic DNA) due to the presence of deletions and mutations that gave rise to premature stop codons. In this work we show that, despite the deletions and mutations, shdA(STy) is fully functional. S. Typhi Delta shdA mutants presented an impaired adherence and invasion of HEp-2 pre-treated with TGF-beta 1, an inducer of fibronectin production. Moreover, shdA from S. Typhi and S. Typhimurium seem to be equivalent since shdA(STm) restored the adherence and invasion of S. Typhi Delta shdA mutant to wild type levels. In addition, anti-FLAG mAbs interfered with the adherence and invasion of the S. Typhi shdA-3xFLAG strain. Finally, shdA(STy) encodes a detectable protein when heterologously expressed in Escherichia coli DH5 alpha. The data presented here show that shdA(STy) is not a pseudogene, but a different functional allele compared with shdA(STm). (C) 2014 Published by Elsevier B. V.