Affiliation:
1. Departments of Biochemistry and of Developmental Biology, Stanford University School of Medicine, Stanford, California 94305-5329
Abstract
ABSTRACT
Cell-bound C-signal guides the building of a fruiting body and triggers the differentiation of myxospores. Earlier work has shown that transcription of the
csgA
gene, which encodes the C-signal, is directed by four genes of the
act
operon. To see how expression of the genes encoding components of the aggregation and sporulation processes depends on C-signaling, mutants with loss-of-function mutations in each of the
act
genes were investigated. These mutations were found to have no effect on genes that are normally expressed up to 3 h into development and are C-signal independent. Neither the time of first expression nor the rate of expression increase was changed in
actA
,
actB
,
actC
, or
actD
mutant strains. Also, there was no effect on A-signal production, which normally starts before 3 h. By contrast, the null
act
mutants have striking defects in C-signal production. These mutations changed the expression of four gene reporters that are related to aggregation and sporulation and are expressed at 6 h or later in development. The
actA
and
actB
null mutations substantially decreased the expression of all these reporters. The other
act
null mutations caused either premature expression to wild-type levels (
actC
) or delayed expression (
actD
), which ultimately rose to wild-type levels. The pattern of effects on these reporters shows how the C-signal differentially regulates the steps that together build a fruiting body and differentiate spores within it.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
37 articles.
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