Regulation of dev, an operon that includes genes essential for Myxococcus xanthus development and CRISPR-associated genes and repeats.
Expression of dev genes is important for triggering spore differentiation inside Myxococcus xanthus fruiting bodies. DNA sequence analysis suggested that dev and cas (CRISPR-associated) genes are cotranscribed at the dev locus, which is adjacent to CRISPR (clustered regularly interspaced short palindromic repeats). Analysis of RNA from developing M. xanthus confirmed that dev and cas genes are cotranscribed with a short upstream gene and at least two repeats of the downstream CRISPR, forming the dev operon. The operon is subject to strong, negative autoregulation during development by DevS. The dev promoter was identified. Its -35 and -10 regions resemble those recognized by M. xanthus sigma(A) RNA polymerase, the homolog of Escherichia coli sigma(70), but the spacer may be too long (20 bp); there is very little expression during growth. Induction during development relies on at least two positive regulatory elements located in the coding region of the next gene upstream. At least two positive regulatory elements and one negative element lie downstream of the dev promoter, such that the region controlling dev expression spans more than 1 kb. The results of testing different fragments for dev promoter activity in wild-type and devS mutant backgrounds strongly suggest that upstream and downstream regulatory elements interact functionally. Strikingly, the 37-bp sequence between the two CRISPR repeats that, minimally, are cotranscribed with dev and cas genes exactly matches a sequence in the bacteriophage Mx8 intP gene, which encodes a form of the integrase needed for lysogenization of M. xanthus.
Viswanathan
Poorna
P
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
Murphy
Kimberly
K
Julien
Bryan
B
Garza
Anthony G
AG
Kroos
Lee
L
D001483:Base Sequence; D004252:DNA Mutational Analysis; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000235:genetics* / Q000254:growth & development; D016366:Open Reading Frames; D009876:Operon / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D013171:Spores, Bacterial / Q000235:genetics*; D014158:Transcription, Genetic
D012329:RNA, Bacterial; D012333:RNA, Messenger