The bldC developmental locus of Streptomyces coelicolor encodes a member of a family of small DNA-binding proteins related to the DNA-binding domains of the MerR family
The bldC developmental locus of Streptomyces coelicolor encodes a member of a family of small DNA-binding proteins related to the DNA-binding domains of the MerR family
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DOI：
10.1128/jb.187.2.716-728.2005
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发表时间：
2005-01-01
影响因子：
3.2
通讯作者：
Buttner, MJ
中科院分区：
文献类型：
--
作者：
Hunt, AC;Servín-González, L;Buttner, MJ
bldC基因座，所需的气生菌丝在天蓝色链霉菌的形成，定位基于图位克隆之间的重叠cosmetic D17和D25的最小有序库。亚克隆和测序表明，bldC编码一个以前未被识别的小（58- 78-残基）DNA结合蛋白家族的成员，与MerR家族的转录激活因子的DNA结合结构域相关。BldC家族成员存在于广泛的革兰氏阳性和革兰氏阴性细菌中。构建的DeltabldC突变体在分化和抗生素生产方面有缺陷。它们在基本培养基上不能形成气生菌丝体，在丰富培养基上表现出严重的气生菌丝体形成延迟。此外，他们未能产生聚酮抗生素放线菌紫素，而bldC被证明是途径特异性激活基因actII-orf 4正常和持续转录所需的。虽然DeltabldC突变体产生三吡咯抗生素十一烷基灵菌红素，但bldC突变体中途径特异性激活基因（redD）的转录物在48小时后减少到几乎检测不到的水平，与bldC（+）亲本菌株相反，bldC（+）亲本菌株中redD转录在气生菌丝体形成和孢子形成期间继续进行。这表明，bldC可能需要在分化过程中维持redD转录。bldC由单个启动子表达。S1核酸酶保护试验和免疫印迹表明，bldC是组成型表达和bldC的转录不依赖于任何其他已知的bld基因。最初定义该基因座的bldC 18突变导致Y 49 C取代，导致蛋白质的不稳定性。
The bldC locus, required for formation of aerial hyphae in Streptomyces coelicolor, was localized by map-based cloning to the overlap between cosmids D17 and D25 of a minimal ordered library. Subcloning and sequencing showed that bldC encodes a member of a previously unrecognized family of small (58- to 78-residue) DNA-binding proteins, related to the DNA-binding domains of the MerR family of transcriptional activators. BldC family members are found in a wide range of gram-positive and gram-negative bacteria. Constructed DeltabldC mutants were defective in differentiation and antibiotic production. They failed to form an aerial mycelium on minimal medium and showed severe delays in aerial mycelium formation on rich medium. In addition, they failed to produce the polyketide antibiotic actinorhodin, and bldC was shown to be required for normal and sustained transcription of the pathway-specific activator gene actII-orf4. Although DeltabldC mutants produced the tripyrrole antibiotic undecylprodigiosin, transcripts of the pathway-specific activator gene (redD) were reduced to almost undetectable levels after 48 h in the bldC mutant, in contrast to the bldC(+) parent strain in which redD transcription continued during aerial mycelium formation and sporulation. This suggests that bldC may be required for maintenance of redD transcription during differentiation. bldC is expressed from a single promoter. S1 nuclease protection assays and immunoblotting showed that bldC is constitutively expressed and that transcription of bldC does not depend on any of the other known bld genes. The bldC18 mutation that originally defined the locus causes a Y49C substitution that results in instability of the protein.