Kg. Payie et al., THE ROLE OF O-ACETYLATION IN THE METABOLISM OF PEPTIDOGLYCAN IN PROVIDENCIA-STUARTII, Microbial drug resistance, 2(1), 1996, pp. 135-140
The gentamicin 2'-N-acetyltransferase [EC 2.3.1.59; AAC(2')-Ia] of Pro
videncia stuartii was shown to contribute to the O-acetylation of pept
idoglycan and mutants that either under- or overexpress the aac(2')-Ia
gene was characterized phenotypically to possess either lower or high
er levels of peptidoglycan O-acetylation, respectively, compared to th
e wild-type, These mutants were subjected to scanning electron microsc
opy, P, stuartii PR100, with 42-44% peptidoglycan O-acetylation compar
ed to 54% for the wild-type, appeared as irregular rods, In direct con
trast, strains PR50.LM3 and PR51, with increased levels of peptidoglyc
an O-acetylation (63 and 65%, respectively), appeared as coccobacilli
or chain formers, respectively, Zymogram analysis of the autolysins pr
oduced by another member of the closely related Proteeae group of bact
eria, Proteus mirabilis, indicated the presence of three classes of en
zymes: one that acts preferentially on native, O-acetylated peptidogly
can, a second that hydrolyses non-O-acetylated peptidoglycan, and a th
ird that is not distinguished by the two forms of substrate, Ou the ba
sis of the apparent morphological changes directly related to levels o
f O-acetylation combined with the presence of different classes of aut
olysins, a model is proposed that invokes the role of this modificatio
n in the control of autolysins for the maintenance of the structure of
the peptidoglycan sacculus.