Helicobacter pylori BabA in adaptation for gastric colonization

Abstract

Helicobacter pylori (H. pylori) as a causative agent of gastric complications, is well adapted for the colonization of gastric mucosa. Although the infectious process depends on several factors, the adhesion to the gastric mucosa is the first and important step. Among several outer membrane proteins, BabA is one of the significant protein involving in many inflammatory processes in addition to its role in the attachment for the persistent colonization. We performed a PubMed search using the key words: "babA", "pylori", "gastric complications", "homologous recombination", "slipped strand mispairing"; a total of 249 articles were displayed. Of these we mainly focused on articles with the full text in English and published between 2005 and 2016. H. pylori BabA is involved in binding with receptors; however, its synthesis is regulated by phase variation. In this review we confirm that H. pylori babA can be modulated at the molecular and functional levels to adapt to the stress within the gastro-intestinal tract.

Keywords: BabA; Gastric complications; Helicobacter pylori; Homologous recombination; Slipped strand mispairing.

Figure 1

In BabA generalists the serine (S) at position 198 makes the DL1 domain to be accessible for the glycan found on blood group A, B as well as O antigen whereas in BabA specialists the replacement of S to leucine (L) makes DL1 to be inaccessible for binding with larger glycans present on blood group A and B antigen.

Figure 2

Cytosine-thiamidine-dinucleotide repeats and slipped strand mis-pairing. Both replicating and template strands are prone to undergo for slippage mis-pairing. Slippage occurring in replicating strand during first generation of replication causes insertion of one CT-dinucleotide in replicating strand whereas the template strand contains original number of CT-dinucleotide. If slippage occurs in template strand during first generation replication, one CT-dinucleotide is deleted in replicating strand to make base paring. During second generation of DNA replication, out of two progeny generating from slippage in replicating strand, one progeny contains DNA with one CT-dinucleotide more than the mother strain while the other progeny contains same number of CT-dinucleotide as mother strain. During second generation of DNA replication, out of two progeny generating from slippage in template strand, one progeny contains DNA with one CT-dinucleotide less than the mother strain while other progeny contains DNA with same number of CT-dinucleotide as do mother strain. CT: Cytosine-thiamidine.