Inducible alkyltransferase DNA repair proteins in the filamentous fungus Aspergillus nidulans.
We have investigated the response of the filamentous fungus Aspergillus nidulans to low, non-killing, doses of the alkylating agent MNNG (N-methyl-N'-nitro-N-nitrosoguanidine). Such treatment causes a substantial induction of DNA alkyltransferase activity, with the specific activity in treated cells increasing up to one hundred-fold. Fluorography reveals the two main inducible species as proteins of 18.5 kDa and 21 kDa, both of which have activity primarily against O6-methylguanine (O6-MeG) lesions. In addition, two other alkyltransferase proteins can also be detected. One, of MW 16 kDa, is expressed in non-treated cells, but is not induced to the same extent as the 18.5 and 21 kDa proteins. The other, a protein of 19.5 kDa, is highly inducible and can only be detected in treated cells. Unlike the other three proteins, it acts primarily against methyl-phosphotriester (Me-PT) lesions. This is the first instance in which an MePT alkyltransferase has been detected in a eukaryotic organism and, coupled with the high level of induction of the O6-MeG alkyltransferase enzymes, this indicates that a control system similar to the bacterial adaptive response may be present in filamentous fungi.
Baker
S M
SM
Department of Genetics and Microbiology, University of Liverpool, UK.
Margison
G P
GP
Strike
P
P
D019883:Alkyl and Aryl Transferases; D001233:Aspergillus nidulans / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004260:DNA Repair; D004271:DNA, Fungal / Q000187:drug effects / Q000378:metabolism; D004586:Electrophoresis; D004790:Enzyme Induction; D008769:Methylnitronitrosoguanidine / Q000633:toxicity*; D008780:Methyltransferases / Q000096:biosynthesis* / Q000378:metabolism; D019853:O(6)-Methylguanine-DNA Methyltransferase; D014166:Transferases / Q000096:biosynthesis* / Q000378:metabolism
D004271:DNA, Fungal; D008769:Methylnitronitrosoguanidine; D014166:Transferases; D008780:Methyltransferases; C045666:methylphosphotriester methyltransferase; D019853:O(6)-Methylguanine-DNA Methyltransferase; D019883:Alkyl and Aryl Transferases; C050956:DNA alkyltransferase