Mm. Schumacher et al., THE OSMOTIC-1 LOCUS OF NEUROSPORA-CRASSA ENCODES A PUTATIVE HISTIDINEKINASE SIMILAR TO OSMOSENSORS OF BACTERIA AND YEAST, Current microbiology, 34(6), 1997, pp. 340-347
Osmotically sensitive mutants of Neurospora crassa are unable to grow
on medium supplemented with 4% NaCl, have altered morphologies and cel
l-wall compositions, and are resistant to dicarboximide fungicides. Os
motic-1 (os-1) mutants have a unique characteristic of forming protopl
asts that grow and divide in specialized liquid medium, suggesting tha
t the os-1(+) gene product is important for cell-wall assembly. A cosm
id containing the os-1(+) locus of N. crassa, isolated from a genomic
cosmid library by chromosomal walk from a closely linked gene, was use
d to subclone the os-li gene by functional complementation of an os-1
mutant. Analysis of the sequence of complementing DNA predicts that os
-1(+) encodes a predicted protein similar to sensor-histidine kinases
of bacteria and a yeast osmosensor-histidine kinase. Importantly, the
predicted os-1(+) protein is identical to the N. crassa nik-1 predicte
d protein that was identified by using polymerase chain reaction prime
rs directed against histidine kinase consensus DNA sequences. Our resu
lts indicate that nik-1 and os-1 encode the same osmosensing histidine
kinase that plays an important role in the regulation of cell-wall as
sembly and, probably, other cell responses to changes in external osmo
larity.