Wed, 20 Aug 2008 22:01:35 BST CiteULike: blobbybirdman Viswanathan http://www.citeulike.org/user/blobbybirdman/author/Viswanathan CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/blobbybirdman/article/2734734 <i>Proceedings of the National Academy of Sciences, Vol. 104, No. 19. (8 May 2007), pp. 7969-7974.</i><br /><br />Myxococcus xanthus is a bacterium that undergoes multicellular development. C-signaling influences gene expression and movement of cells into aggregates. Expression of the dev operon, which includes genes essential for efficient sporulation, depends in part on C-signaling and reaches its highest level in cells within aggregates, ensuring that spores form within fruiting bodies. Here, an upstream DNA element was found to be essential for dev promoter activity and was bound by FruA, a response regulator in the C-signaling pathway. A second positive regulatory element, located approx350 bp downstream of the dev transcriptional start site, was bound by LadA, a newly identified transcription factor in the LysR family. Typically, LysR-type transcription factors bind upstream of the promoter and activate transcription in response to a coinducer. LadA appears to activate transcription from an unusual location for a LysR family member and likely subjects dev transcription to a different cue than does FruA. A ladA mutant exhibited similar developmental defects as dev mutants, suggesting that LadA may be devoted to dev regulation, unlike FruA, which regulates many developmental genes. FruA and LadA act on a regulatory region spanning >400 bp to bring about proper temporal and spatial expression of the dev operon, resembling the regulation of developmental genes in multicellular eukaryotes. 10.1073/pnas.0701569104 Combinatorial regulation of genes essential for Myxococcus xanthus development involves a response regulator and a LysR-type regulator Poorna Viswanathan Toshiyuki Ueki Sumiko Inouye Lee Kroos doi:10.1073/pnas.0701569104 Proceedings of the National Academy of Sciences, Vol. 104, No. 19. (8 May 2007), pp. 7969-7974. 2008-04-29T15:42:17-00:00 2007 Proceedings of the National Academy of Sciences 104 19 7969 7974 development gene-regulation m_xanthus myxobacteria response-regulators http://www.citeulike.org/user/blobbybirdman/article/1284500 <i>J Bacteriol, Vol. 189, No. 10. (May 2007), pp. 3738-3750.</i><br /><br />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. Regulation of dev, an Operon That Includes Genes Essential for Myxococcus xanthus Development and CRISPR-Associated Genes and Repeats. P Viswanathan K Murphy B Julien AG Garza L Kroos doi:10.1128/JB.00187-07 J Bacteriol, Vol. 189, No. 10. (May 2007), pp. 3738-3750. 2007-05-09T04:06:16-00:00 2007 J Bacteriol 0021-9193 189 10 3738 3750 development gene-regulation m_xanthus