The AmpC ß-lactamase is present in many Gram-negative bacteria, and can be induced to high levels by ß-lactam antibiotics. This induction is a major factor of ß-lactam resistance by these organisms. The induction process involves several structural and regulatory genes. The ampG gene appears to play a key role, presumably as membrane-bound transducer of the external induction signal to the intracellular ß-lactamase regulon (Korfmann, 1989). The transducer appears to relay the signal to the ampR-encoded transcriptional regulator, which activates the transcription of the structural gene ampC. The role of ampG in ampC activity must be viewed within the observation that the primary function of AmpG is as a cytoplasmic membrane protein required for recycling of murein tripeptideas part of bacterial cell wall recycling.
Within Orientia the gene ampG1 appears to be the homologous locus to ampG genes in other taxa. An examination of the genomes of 14 O. tsutsugamushi isolates and the genome of O. chuto show that all contain an apparent intact ampG1, but show variation at both the nucleic acid and amino levels.
The location of the ampG1 locus in the genome of the Boryong isolate is at positions 490445..491707.