Disease relevance of blaI

• A blaI probe from pI524 was hybridized with plasmid and genomic DNA from Bla+ Enterococcus faecalis isolates HH22 and PA [1].
• The precise start points for transcription of the blaZ and of the blaRI/blaI genes of the Staphylococcus aureus beta-lactamase operon have been determined by primer extension analysis [2].
• In the present study,we followed the fate of BlaI during beta-lactamase induction in B. licheniformis 749/I and in a recombinant Bacillus subtilis 168 strain harbouring the pDML995 plasmid, which carries the B. licheniformis blaP, blaI and blaRl genes [3].

High impact information on blaI

• In both bacteria, the products of the blaI and blaRl genes share a high degree of sequence homology and act as repressors and penicillin-sensory transducers respectively [3].
• The production of PBP2' is under dual control by its own mecR1-mecI- and the penicillinase blaR1-blaI-encoded regulatory elements [4].
• The putative beta-lactamase (Bla) repressor gene, blaI, from the staphylococcal plasmid pI524 was isolated, and the DNA sequence was determined [1].
• In contrast, mecI repression seemed to be partially or fully retained in many of the isolates with mecI and one isolate with blaI missense mutations, providing structure-function correlates with the site and type of mutation [5].
• 5-methyltryptophan seems to induce penicillinase synthesis in wild-type plasmids by becoming incorporated into the repressor and thereby inactivating the operator binding function of the penicillinase repressor [6].

Other interactions of blaI

• The mec and bla regulators, mecR1-mecI and blaR1-blaI, respectively, encode inducer-repressors with sufficient amino acid homology to suggest that they could coregulate PBP2a production [7].

Analytical, diagnostic and therapeutic context of blaI

• Northern blots showed that the synthesis of the 2100 nt mRNA from blaRI is inducible and that a blaI probe hybridized to the same mRNA as the blaRI probe [2].
• Sequence analysis of the beta-lactamase repressor from Staphylococcus aureus and hybridization studies with two beta-lactamase-producing isolates of Enterococcus faecalis [1].

References