Mutations of the Act Promoter in
            <i>Myxococcus xanthus</i>

Gronewold, Thomas M. A.; Kaiser, Dale

doi:10.1128/jb.01618-06

Cited by 21 publications

(20 citation statements)

References 74 publications

(74 reference statements)

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“…3 A-C suggest that transcription of the nla6, nla28, and actB operons is also subjected to autoregulation; Nla6-DBD, Nla28-DBD, and ActB-DBD were capable of binding to fragments containing the promoter regions of the nla6, nla28, and actB operons, respectively. These findings are consistent with previous work showing that expression of genes in the actB operon is reduced in an actB mutant (34). They are also consistent with the data in Fig.…”

Section: Preaggregation and Aggregation Ebp Genes Are Expressed Insupporting

confidence: 83%

A cascade of coregulating enhancer binding proteins initiates and propagates a multicellular developmental program

Giglio

Caberoy

Suen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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139

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The signal transduction networks that initiate multicellular development in bacteria remain largely undefined. Here, we report that Myxococcus xanthus regulates entry into its multicellular developmental program using a novel strategy: a cascade of transcriptional activators known as enhancer binding proteins (EBPs). The EBPs in the cascade function in sequential stages of early development, and several lines of evidence indicate that the cascade is propagated when EBPs that function at one stage of development directly regulate transcription of an EBP gene important for the next developmental stage. We also show that the regulatory cascade is designed in a novel way that extensively expands on the typical use of EBPs: Instead of using only one EBP to regulate a particular gene or group of genes, which is the norm in other bacterial systems, the cascade uses multiple EBPs to regulate EBP genes that are positioned at key transition points in early development. Based on the locations of the putative EBP promoter binding sites, several different mechanisms of EBP coregulation are possible, including the formation of coregulating EBP transcriptional complexes. We propose that M. xanthus uses an EBP coregulation strategy to make expression of EBP genes that modulate stage-stage transitions responsive to multiple signal transduction pathways, which provide information that is important for a coordinated decision to advance the developmental process.

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Section: Preaggregation and Aggregation Ebp Genes Are Expressed Insupporting

confidence: 83%

A cascade of coregulating enhancer binding proteins initiates and propagates a multicellular developmental program

Giglio

Caberoy

Suen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

139

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“…We also showed that the mutations in the putative Nla6 enhancer in the nla28 promoter reduce its in vivo activity during development. It is noteworthy that previous experimental analyses indicate that the actB, asgE, nla6, and nla28 operons use 54 promoter elements (13,40,47), which are the targets of EBP-mediated regulation. In addition, the remaining promoters that were positive for Nla6 DBD binding contain sequences that are good matches to the 54 promoter consensus (14).…”

Section: Discussionmentioning

confidence: 99%

The Enhancer Binding Protein Nla6 Regulates Developmental Genes That Are Important for Myxococcus xanthus Sporulation

et al. 2015

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In the bacterium Myxococcus xanthus, starvation triggers the formation of multicellular fruiting bodies containing thousands of stress-resistant spores. Recent work showed that fruiting body development is regulated by a cascade of transcriptional activators called enhancer binding proteins (EBPs). The EBP Nla6 is a key component of this cascade; it regulates the promoters of other EBP genes, including a downstream-functioning EBP gene that is crucial for sporulation. In recent expression studies, hundreds of Nla6-dependent genes were identified, suggesting that the EBP gene targets of Nla6 may be part of a much larger regulon. The goal of this study was to identify and characterize genes that belong to the Nla6 regulon. Accordingly, a direct repeat [consensus, C(C/A)ACGNNGNC] binding site for Nla6 was identified using in vitro and in vivo mutational analyses, and the sequence was subsequently used to find 40 potential developmental promoter (88 gene) targets. We showed that Nla6 binds to the promoter region of four new targets (asgE, exo, MXAN2688, and MXAN3259) in vitro and that Nla6 is important for their normal expression in vivo. Phenotypic studies indicate that all of the experimentally confirmed targets of Nla6 are primarily involved in sporulation. These targets include genes involved in transcriptional regulation, cell-cell signal production, and spore differentiation and maturation. Although sporulation occurs late in development, all of the developmental loci analyzed here show an Nla6-dependent burst in expression soon after starvation is induced. This finding suggests that Nla6 starts preparing cells for sporulation very early in the developmental process. IMPORTANCEBacterial development yields a remarkable array of complex multicellular forms. One such form, which is commonly found in nature, is a surface-associated aggregate of cells known as a biofilm. Mature biofilms are structurally complex and contain cells that are highly resistant to antibacterial agents. When starving, the model bacterium Myxococcus xanthus forms a biofilm containing a thin mat of cells and multicellular structures that house a highly resistant cell type called a myxospore. Here, we identify the promoter binding site of the transcriptional activator Nla6, identify genes in the Nla6 regulon, and show that several of the genes in the Nla6 regulon are important for production of stress-resistant spores in starvation-induced M. xanthus biofilms. Bacterial development yields a remarkable array of complex multicellular forms. Arguably, one of the most interesting forms of bacterial multicellularity is a surface-associated aggregate of cells known as a biofilm (1). Mature biofilms are complex and often contain highly ordered structural features, such as towers of cells. Particular sets of genes must be expressed at each stage in the development of biofilms; however, the regulation and function of such genes are not well understood in the vast majority of bacteria. In this study, we identified a set of developmental promote...

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“…Because of the positive feedback, there is a progressive increase in the cell surface level of Csignal. The five proteins of the act operon increase expression of the csgA gene (Gronewold and Kaiser 2007). At the start of development, there are few C-signal molecules per cell.…”

Section: C-signaling and Developmentmentioning

confidence: 99%

Myxobacteria, Polarity, and Multicellular Morphogenesis

Kaiser¹,

Robinson²,

Kroos³

2010

Cold Spring Harbor Perspectives in Biology

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Myxobacteria are renowned for the ability to sporulate within fruiting bodies whose shapes are species-specific. The capacity to build those multicellular structures arises from the ability of M. xanthus to organize high cell-density swarms, in which the cells tend to be aligned with each other while constantly in motion. The intrinsic polarity of rod-shaped cells lays the foundation, and each cell uses two polar engines for gliding on surfaces. It sprouts retractile type IV pili from the leading cell pole and secretes capsular polysaccharide through nozzles from the trailing pole. Regularly periodic reversal of the gliding direction was found to be required for swarming. Those reversals are generated by a G-protein switch which is driven by a sharply tuned oscillator. Starvation induces fruiting body development, and systematic reductions in the reversal frequency are necessary for the cells to aggregate rather than continue to swarm. Developmental gene expression is regulated by a network that is connected to the suppression of reversals.

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Mutations of the Act Promoter in Myxococcus xanthus

Cited by 21 publications

References 74 publications

A cascade of coregulating enhancer binding proteins initiates and propagates a multicellular developmental program

A cascade of coregulating enhancer binding proteins initiates and propagates a multicellular developmental program

The Enhancer Binding Protein Nla6 Regulates Developmental Genes That Are Important for Myxococcus xanthus Sporulation

Myxobacteria, Polarity, and Multicellular Morphogenesis

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