title: aarC, an essential gene involved in density-dependent regulation of the 2'-N-acetyltransferase in Providencia stuartii.
abstract: The 2'-N-acetyltransferase [AAC(2')-Ia] in Providencia stuartii has a dual function where it is involved in the acetylation of peptidoglycan and certain aminoglycosides. A search for negative regulators of the aac(2')-Ia gene has resulted in the identification of aarC. A missense allele (aarC1) resulted in an 8.9-fold increase in beta-galactosidase accumulation from an aac(2')-lacZ transcriptional fusion. Northern blot analysis demonstrated an increase in aac(2')-Ia mRNA accumulation that was specific to cells at high density. In addition, the aarC1 allele also resulted in a substantial increase in the expression of aarP, a transcriptional activator of the aac(2')-Ia gene. The wild-type aarC gene was isolated by complementation and encodes a predicted protein of 365 amino acids with a molecular mass of 39,815 Da. The predicted AarC protein exhibited 88% amino acid homology to the previously identified GcpE protein of Escherichia coli and 86% homology to a gene product from Haemophilus influenzae. The E. coli gcpE gene was able to functionally complement the aarC1 allele in P. stuartii. The aarC1 allele was identified as a T to G transversion that resulted in a valine to glycine substitution at position 136 in the AarC protein. The aarC gene appears to be essential for cell viability as construction of a disrupted copy (aarC::lacZ) was possible only in cells that carried an episomal copy of aarC or gcpE.
authors.affiliation: Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
authors.forename: P N
authors.initials: PN
authors.lastname: Rather
authors.forename: K A
authors.initials: KA
authors.lastname: Solinsky
authors.forename: M R
authors.initials: MR
authors.lastname: Paradise
authors.forename: M M
authors.initials: MM
authors.lastname: Parojcic
mesh_terms: D000123:Acetyltransferases / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D011532:Providencia / Q000201:enzymology / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: C105284:AarC protein, Providencia stuartii; C093833:AarP protein, Providencia stuartii; D001426:Bacterial Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D000123:Acetyltransferases