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- Crystal structure of the inactive state of the receiver domain of Spo0A from Paenisporosarcina sp. TG-14, a psychrophilic bacterium isolated from an Antarctic glacier
- Chang Woo Lee , Sun-Ha Park , Sung Gu Lee , Seung Chul Shin , Se Jong Han , Han-Woo Kim , Hyun Ho Park , Sunghwan Kim , Hak Jun Kim , Hyun Park , HaJeung Park , Jun Hyuck Lee
- J. Microbiol. 2017;55(6):464-474. Published online March 9, 2017
- DOI: https://doi.org/10.1007/s12275-017-6599-9
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Abstract
- The two-component phosphorelay system is the most pre-valent mechanism for sensing and transducing environ-mental signals in bacteria. Spore formation, which relies on the two-component phosphorelay system, enables the long- term survival of the glacial bacterium Paenisporosarcina sp. TG-14 in the extreme cold environment. Spo0A is a key re-sponse regulator of the phosphorelay system in the early stage of spore formation. The protein is composed of a regu-latory N-terminal phospho-receiver domain and a DNA- binding C-terminal activator domain. We solved the three- dimensional structure of the unphosphorylated (inactive) form of the receiver domain of Spo0A (PaSpo0A-R) from Paenisporosarcina sp. TG-14. A structural comparison with phosphorylated (active form) Spo0A from Bacillus stearo-thermophilus (BsSpo0A) showed minor notable differences. A molecular dynamics study of a model of the active form and the crystal structures revealed significant differences in the α4 helix and the preceding loop region where phosphorylation occurs. Although an oligomerization study of PaSpo0A-R by analytical ultracentrifugation (AUC) has shown that the protein is in a monomeric state in solution, both crosslinking and crystal-packing analyses indicate the possibility of weak dimer formation by a previously undocumented mechanism. Collectively, these observations provide insight into the me-chanism of phosphorylation-dependent activation unique to Spo0A.
Research Support, Non-U.S. Gov'ts
- Cytochrome c_550 is Related to Initiation of Sporulation in Bacillus subtilis
- Inji Shin , Han-Bong Ryu , Hyung-Soon Yim , Sa-Ouk Kang
- J. Microbiol. 2005;43(3):244-250.
- DOI: https://doi.org/2218 [pii]
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Abstract
- The effect of cytochrome c_550 encoded by cccA in Bacillus subtilis during the event of sporulation was investigated. The sporulation of cccA-overexpressing mutant was significantly accelerated, while disruptant strain showed delayed sporulation in spite of the same growth rate. Activity of sporulation stage-0-specific enzyme, extracellular [alpha]-amylase of mutant strains was similar to that of the control strain, but cccA-overexpressing mutant exhibited higher activity of stage-II-specific alkaline phosphatase and stage-III-specific glucose dehydrogenase when compared to deletion mutant and control strain. Northern blot analysis also revealed that cccA-overexpressing mutant showed high level of spo0A transcripts, while the disruptant rarely expressed spo0A. These results suggested that although cytochrome c_550 is dispensable for growth and sporulation, expression of cccA may play an important role for initiation of sporulation through regulation of spo0A expression.
- Expression of the Promoter for the Maltogenic Amylase Gene in Bacillus subtilis 168
- Do-Yeon Kim , Choon-Hwan Cha , Wan-Seok Oh , Young-Jun Yoon , Jung-Wan Kim
- J. Microbiol. 2004;42(4):319-327.
- DOI: https://doi.org/2104 [pii]
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Abstract
- An additional amylase, besides the typical a-amylase, was detected for the first time in the cytoplasm of B. subtilis SUH4-2, an isolate from Korean soil. The corresponding gene (bbmA) encoded a maltogenic amylase (MAase) and its sequence was almost identical to the yvdF gene of B. subtilis 168, whose function was unknown. Southern blot analysis using bbmA as the probe indicated that this gene was ubiquitous among various B. subtilis strains. In an effort to understand the physiological function of the bbmA gene in B. subtilis, the expression pattern of the gene was monitored by measuring the [beta]-galactosidase activity produced from the bbmA promoter fused to the amino terminus of the lacZ structural gene, which was then integrated into the amyE locus on the B. subtilis 168 chromosome. The promoter was induced during the mid-log phase and fully expressed at the early stationary phase in defined media containing [beta]-cyclodextrin ([beta]-CD), maltose, or starch. On the other hand, it was kept repressed in the presence of glucose, fructose, sucrose, or glycerol, suggesting that catabolite repression might be involved in the expression of the gene. Production of the [beta]-CD hydrolyzing activity was impaired by the spo0A mutation in B. subtilis 168, indicating the involvement of an additional regulatory system exerting control on the promoter. Inactivation of yvdF resulted in a significant decrease of the [beta]-CD hydrolyzing activity, if not all. This result implied the presence of an additional enzyme(s) that is capable of hydrolyzing [beta]-CD in B. subtilis 168. Based on the results, MAase encoded by bbmA is likely to be involved in maltose and [beta]-CD utilization when other sugars, which are readily usable as an energy source, are not available during the stationary phase.
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