Disease relevance of hlyB

• Thus, the evolutionarily conserved family of MDR-like genes, including the hlyB gene of Escherichia coli and the STE6 gene of S. cerevisiae, encodes components of secretory pathways distinct from the classical, signal sequence-dependent protein translocation system [1].
• The prokaryotic hlyB gene product is a member of a superfamily of ATP-binding transport proteins that include the eukaryotic multidrug-resistance P-glycoprotein, the yeast STE6, and the cystic fibrosis CFTR gene products (Juranka, P. F., Zastawny, R. L., and Ling, V. (1989) FASEB J. 3, 2583-2592) [2].
• The hlyB secretion genes of Proteus vulgaris and Escherichia coli showed 81% nucleotide homology and similar E. coli-atypical codon usage [3].
• Mutations in hlyB affecting secretion could be assigned to two classes: those that restore the level of vancomycin resistance to that of E. coli not secreting HlyA and those that still confer hypersensitivity to the drug in the presence of HlyA [4].

High impact information on hlyB

• The fragment contains four transcribed and translated genes: inh, which codes for a protease inhibitor and is not required for protease secretion, and prtD, prtE and prtF, which share significant homology with the hlyB, hlyD and tolC genes required for alpha-haemolysin secretion in Escherichia coli [5].
• Southern hybridization of A. pleuropneumoniae parental DNA nevertheless indicated only a low degree of nucleotide sequence identity to the haemolysin structural and secretion genes hlyA and hlyB of E. coli [6].
• Expression of the E.coli hemolysin secretion gene hlyB involves transcript anti-termination within the hly operon [7].
• An Escherichia coli strain with wild-type hemolysin secretion genes hlyB and hlyD and containing a cloned frpA gene secreted FrpA, whereas an isogenic hlyBD mutant strain did not [8].
• The predicted pedD protein shows strong similarities to several ATP-dependent transport proteins, including the E. coli hemolysin secretion protein HlyB and the ComA protein, which is required for competence induction for genetic transformation in Streptococcus pneumoniae.(ABSTRACT TRUNCATED AT 250 WORDS)[9]

Biological context of hlyB

• In addition several other similar or even identical sequences are found in the vicinity of the hlyC- and the hlyB-distal ends of both the chromosomal and the plasmid hly determinants [10].
• Second-site suppressor mutations in hlyD and hlyB were obtained, which abolish the hypersensitive phenotype caused by the 3'-terminal mutations in hlyD [11].

Anatomical context of hlyB

• (iv) Active hemolysin remains in the periplasm in the absence of hlyB function, hence the hlyB product seems to be necessary for the transport of hemolysin to the exterior of the cell [12].

References