J Bacteriol, April 1998, p. 1995-2004, Vol. 180, No. 8
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
4400 Regulatory Region, a
Developmental Promoter of Myxococcus xanthus
Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824
Received 2 October 1997/Accepted 11 February 1998
4400 is the site of a Tn5 lac insertion in the
Myxococcus xanthus genome that fuses lacZ
expression to a developmentally regulated promoter. Cell-cell
interactions that occur during development, including C signaling, are
required for normal expression of Tn5 lac
4400. The DNA
upstream of the
4400 insertion has been cloned, the promoter has
been localized, and a partial open reading frame has been identified.
From the deduced amino acid sequence of the partial open reading frame,
the gene disrupted by Tn5 lac
4400 may encode a protein
with an ATP- or GTP-binding site. Expression of the gene begins 6 to
12 h after starvation initiates development, as measured by
-galactosidase production in cells containing Tn5 lac
4400. The putative transcriptional start site was mapped, and
deletion analysis has shown that DNA downstream of
101 bp is
sufficient for C-signal-dependent, developmental activation of this
promoter. A deletion to
76 bp eliminated promoter activity, suggesting the involvement of an upstream activator protein. The promoter may be transcribed by RNA polymerase containing a novel sigma
factor, since a mutation in the M. xanthus sigB or
sigC gene did not affect Tn5 lac
4400
expression and the DNA sequence upstream of the transcriptional start
site did not match the sequence of any M. xanthus promoter
transcribed by a known form of RNA polymerase. However, the
4400
promoter does contain the sequence 5'-CATCCCT-3' centered at
49 and the C-signal-dependent
4403 promoter also contains this
sequence at the same position. Moreover, the two promoters match at
five of six positions in the
10 regions, suggesting that these
promoters may share one or more transcription factors. These results
begin to define the cis-acting regulatory elements
important for cell-cell interaction-dependent gene expression during
the development of a multicellular prokaryote.
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