RESUMO
The nucleotide cyclic di-GMP is a second messenger in bacteria that regulates a range of cellular functions including the virulence of pathogens. GGDEF is a protein domain involved in the synthesis of cyclic di-GMP. The genome of the crucifer pathogen Xanthomonas campestris pv. campestris (Xcc) encodes 21 proteins with a GGDEF domain. Clp, a homolog of the model transcription factor Crp of Escherichia coli, is a global regulator in Xcc. The aim of this study is to identify genes encoding GGDEF domain proteins whose expression is regulated by Clp. Results of reporter assay and RT-PCR analysis suggested that Clp regulates the expression of a set of genes encoding proteins harboring GGDEF domain. The transcription initiation site of XCC1294, one of the Clp regulated gene encoding a GGDEF domain protein, was mapped. Promoter analysis and gel retardation assay indicated that the transcription of XCC1294 is positively and directly regulated by Clp. Furthermore, transcription of XCC1294 was subject to catabolite repression and affected by several stress conditions. We also showed that mutation of XCC1294 results in enhanced surface attachment. In addition, transcription of three putative adhesin genes (xadA, fhaC, and yapH) was increased in the XCC1294 mutant. Taken together, the data presented here indicate that Clp positively regulates expression of XCC1294, and that XCC1294 serves a regulator of bacterial attachment and regulates different adhesin genes expression.
Assuntos
Proteínas de Bactérias/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Virulência/metabolismo , Xanthomonas campestris/genética , Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Sequência de Bases , Brassica/microbiologia , Mapeamento Cromossômico , Escherichia coli/genética , Escherichia coli/metabolismo , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Teste de Complementação Genética , Dados de Sequência Molecular , Mutação , Regiões Promotoras Genéticas , Estrutura Terciária de Proteína , Sítio de Iniciação de Transcrição , Virulência , Fatores de Virulência/genética , Xanthomonas campestris/metabolismo , Xanthomonas campestris/patogenicidadeRESUMO
Metal-dielectric multiple-band high-reflection coatings are designed as induced filters and fabricated by reactive deposition. Ta(2)O(5) and SiO(2) are used as high- and low-refractive-index layers, and Cr and Al are used as bonding and reflective layers, respectively, for constructing the filters. The metal-dielectric coatings are deposited on a light-shaping flexible plastic substrate for use as a screen with high-contrast enhancement performance. This screen was suitable for miniprojectors with red, green, and blue LEDs as light sources. Mechanical properties such as stress, hardness, and adhesive strength of these multilayer films are investigated also.
