Disease relevance of hlyA

• This revealed two open reading frames which shared approximately 60% homology to the hlyC and hlyA genes of the E. coli alpha-hemolysin (alpha-hly) operon [1].
• Transcription of the Vibrio cholerae hlyA gene, which encodes a cytotoxic haemolysin, has been investigated [2].
• Furthermore, the restriction fragment length polymorphisms detected with probes flanking the hlyA gene may be useful epidemiological markers in identifying and distinguishing virulent Listeria strains from each other [3].
• Locus of enterocyte effacement genes were detected in 24% of the isolates, and enterohemorrhagic E. coli (EHEC) hlyA genes were detected in 72% of the isolates [4].
• The isolate belonged to phage type 21/28 and possessed vtx2, eaeA, and enterohemorrhagic E. coli hlyA genes [5].

High impact information on hlyA

• Fusion of the C-terminal 53 amino acid sequence to non-exported truncated Hly A directed wild-type export but export was radically reduced following independent disruption or progressive truncation of the three C-terminal features by in-frame deletion and the introduction of translation stop codons within the 3' hlyA sequence [6].
• The hemolytic activity of the mutant organism was markedly decreased; the product of the hlyA delta pro gene, secreted in the periplasm, was degraded [7].
• An hlyA-cat fusion was used to select, from a V. cholerae O17 plasmid library, a clone that could activate the hlyA promoter in E. coli [2].
• Nucleotide sequence analysis has demonstrated that hlyA encodes a protein of Mr 82,250 with a potential 18-amino-acid signal sequence [8].
• The hlyB and hlyA genes are organized in an operon that is coordinately regulated by iron and oxygen [9].

Biological context of hlyA

• Prior cold or cold-acid stress had no effect on virulence factor production (P > 0.05), although growth in acidic media (pH 5.5) enhanced eaeA and hlyA expression (P < 0.05) [10].
• Isolates possessed the E. coli attaching and effacing gene (eaeA), and hemolysin gene (hlyA), and harbored 3.0-MDa and 60-MDa plasmids [11].
• Pathogenicity of an enterotoxigenic Escherichia coli hemolysin (hlyA) mutant in gnotobiotic piglets [12].
• Nucleotide sequence analysis of hlyA revealed an open reading frame consisting of 2,223 bp which can code for a protein of 741 amino acids with a molecular weight of 81,961 [13].
• Taken together, these results suggest that iron and oxidative stress have an effect on the control of hlyBA and hlyA transcriptional levels [9].

Anatomical context of hlyA

• Proteolysis of the product of the hlyA gene occurred but was not required for transport of the protein through the cell wall [14].
• Two (hlyC and hlyA) determine the synthesis of a hemolytically active protein which is transported across the cytoplasmic membrane [15].
• Permeability increase induced by Escherichia coli hemolysin A in human macrophages is due to the formation of ionic pores: a patch clamp characterization [16].

Associations of hlyA with chemical compounds

• Two site-specific mutations at the N-terminal end of hlyA (one at amino acid position 2 leading to a thr----pro exchange and another deleting ile and thr at positions 4 and 5) also do not affect the transport of the altered haemolysins [17].
• The main finding was that the absence of E-hly might be compensated for by the gene iutA coding for aerobactin or hlyA coding for alpha-haemolysin as 94% of the human VTEC isolates had at least one of these genes [18].

Other interactions of hlyA

• The newly discovered genes together with the EHEC hlyC and hlyA genes constitute a typical RTX (Repeats in ToXin) determinant (EHEC hly operon) with the gene order CABD [19].
• The probes include parts of apxIA, apxIIA, and apxIIIA from Actinobacillus pleuropneumoniae, cyaA from Bordetella pertusis, frpA from Neisseria meningitidis, prtC from Erwinia chrysanthemi, hlyA and elyA from Escherichia coli, aaltA from Actinobacillus actinomycetemcomitans and lktA from Pasteurella haemolytica [20].
• Finally, we were able to reconstitute the complete haemolysin system from three different plasmids encoding hlyC, hlyA and hlyB + hlyD, respectively [21].

Analytical, diagnostic and therapeutic context of hlyA

• Genotyping was made up of confirmation of the presence of the O157 antigen (rfb), the H7 antigen (ficC), the adherence factor (eaeA), hemolysin (hlyA), and VT production (vt I and vt II) by polymerase chain reaction. mTSB gave better enrichment for E. coli O157 than gram-negative (GN) broth [22].
• The 82- and 79-kDa precursors of the 65-kDa mature cytolysin were found in V. cholerae by pulse-chase labeling and Western blot (immunoblot) analysis of hlyA products [13].
• In vitro-derived recombinant hybrid genes between hlyA and lktA were constructed by using restriction endonuclease sites created by oligonucleotide site-directed mutagenesis [23].
• Restriction mapping and Southern blot analysis revealed that lec, hlyA (hemolysin), and hlyC (lipase) are adjacent on the V. cholerae chromosome, and chromosomal digests of several El Tor, classical, and O139 (Bengal) strains demonstrated conservation of this gene arrangement [24].
• E. coli O157:H7 isolates were fingerprinted by pulsed-field gel electrophoresis and subjected to multiplex PCR procedures for amplification of E. coli O157:H7 genes stx1, stx2, eaeA, fliC, rfbEO157, and hlyA [25].

References