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aarD , a Providencia stuartii homologue of cydD : role in 2′‐ N ‐acetyltransferase expression, cell morphology and growth in the presence of an extracellular factor
Author(s) -
Macinga David R.,
Rather Philip N.
Publication year - 1996
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1996.385912.x
Subject(s) - biology , mutant , open reading frame , microbiology and biotechnology , extracellular , genetics , locus (genetics) , escherichia coli , gene , peptide sequence
In a search for genes involved in regulation of the 2′‐ N ‐acetyltransferase in Providencia stuartii , a mini‐Tn 5 Cm insertion has been isolated in a locus designated aarD . The aarD1 ::mini‐Tn 5 Cm mutation resulted in a 4.7‐fold increase in the levels of β‐galactosidase accumulation from an aac(2′)–lacZ transcriptional fusion and a 32‐fold increase in the levels of gentamicin resistance in P. stuartii . The wild‐type aarD locus was cloned on a 5.0 kb Cla I fragment and complemented the aarD1 mutation. Nucleotide sequence analysis of this fragment identified two large open reading frames whose deduced products displayed significant amino acid identity, 64% and 64%, respectively, to the CydD and CydC proteins of Escherichia coli , which are involved in formation of the cytochrome d oxidase complex. Physical mapping indicated the aarD1 ::mini‐Tn 5 Cm insertion was within the open reading homologous to CydD. The strain containing the aarD1 mutation was unable to grow in the presence of toluidine blue or on glycerol minimal media in the presence of zinc, suggesting that aarD is functionally equivalent to cydD . Additional phenotypes resulting from the aarD1 mutation included: altered cell morphology, a reduced growth rate and the inability of cells to grow beyond early log phase. Further examination of this phenomenon revealed that the aarD1 mutant was unable to grow in the presence of a self‐produced extracellular factor(s). This novel phenotype was not limited to P. stuartii as E. coli cydD and Δ cydAB :: kan mutants were also sensitive to a self‐produced extracellular factor.