Bol'shakov M A, Ashikhmin A A, Makhneva Z K, Moskalenko A A
Mikrobiologiia. 2016 Jul;85(4):403-414.
Effect of illumination intensity and inhibition of carotenoid biosynthesis on assemblage of different spectral types of LH2 complexes in a purple sulfur bacterium Allochromatium (Alc.) vinosum ATCC 17899 was studied. Under illumination of 1200 and 500 lx, the complexes B800-850 and B800-840 and B800-820 were assembled. While rhodopine was the major carotenoid in all spectral types of the LH2 complex, a certain- increase in the content of carotenoids with higher numbers of conjugated double bonds (anhydrorhodovibrin and didehydrorhodovibrin) was observed in the B800-820 complex. At 1200 lx, the cells grew slowly at diphe- nylamine (DPA) concentrations not exceeding 53 .iM, while at illumination intensity decreased to 500 Ix they could grow at 71 jiM DPA (DPA cells). Independent on illumination level, the inhibitor is supposed to impair the functioning of phytoine synthetase (resulting in a decrease in the total carotenoid content) and of phyto- ine desturase, which results in formation of neurosporene hydroxy derivatives and ;-carotene. In the cells grown at 500 lx, small amounts of spheroidene and.OH-spheroidene were detected. These carotenoids were originally found under conditions of carotenoid synthesis inhibition in bacteria with spirilloxanthin as the major carotenoid. Carotenoid content in the LH2 complexes isolated from the DPA cells was -15% of the control (without inhibition) for the B800-850 and -20%of the control for the B800-820 and B800-840 DPA complexes. Compared to the DPA pigment-containing membranes, the DPA complexes were enriched with -carotenoids due to- disintegration of some carotenoid-free complexes in the course of isolation. These results support the supposition that some of the B800-820, B800-840, and B800-850 complexes may be Assembled in the cells of Alc. vinosum ATCC 17899 without carotenoids. Comparison of the characteristics obtained for Alc. vinosum ATCC 17899 and the literature data on strain D of the same bacteria shows that they belong to two different strains, rather than to one as was previously supposed.
研究了光照强度和类胡萝卜素生物合成抑制对紫色硫细菌嗜酒嗜色菌（Allochromatium (Alc.) vinosum）ATCC 17899中不同光谱类型LH2复合物组装的影响。在1200勒克斯和500勒克斯光照下，组装了B800 - 850、B800 - 840和B800 - 820复合物。虽然视紫红质是所有光谱类型LH2复合物中的主要类胡萝卜素，但在B800 - 820复合物中观察到共轭双键数量较多的类胡萝卜素（脱水视紫红素和双脱水视紫红素）含量有一定增加。在1200勒克斯时，细胞在二苯胺（DPA）浓度不超过53 μM时生长缓慢，而当光照强度降至500勒克斯时，它们在71 μM DPA（DPA细胞）下仍能生长。与光照水平无关，该抑制剂被认为会损害植醇合成酶的功能（导致总类胡萝卜素含量降低）以及植醇去饱和酶的功能，这会导致神经孢烯羟基衍生物和β - 胡萝卜素的形成。在500勒克斯下生长的细胞中，检测到少量的球形烯和羟基球形烯。这些类胡萝卜素最初是在以螺菌黄素为主要类胡萝卜素的细菌中，在类胡萝卜素合成抑制条件下发现的。从DPA细胞中分离出的LH2复合物中的类胡萝卜素含量，对于B800 - 850复合物是对照（无抑制）的 - 15%，对于B800 - 820和B800 - 840 DPA复合物是对照的 - 20%。与含DPA色素的膜相比，由于在分离过程中一些不含类胡萝卜素的复合物解体，DPA复合物富含β - 胡萝卜素。这些结果支持了这样的推测，即一些B800 - 820、B800 - 840和B800 - 850复合物可能在嗜酒嗜色菌ATCC 17899的细胞中在没有类胡萝卜素的情况下组装。对嗜酒嗜色菌ATCC 17899获得的特征与同一细菌菌株D的文献数据进行比较表明，它们属于两个不同的菌株，而不是像之前认为的那样属于同一菌株。
