Studies on Vitamin K Biosynthesis

DESCRIPITON(申请人提供)：人类和动物不能合成 维生素K(K)。钾依赖、血栓原减少是一个重要的临床问题。 在许多情况下。人和动物营养中的钾需求 受到绿色植物和肠道细菌的影响。因为K扮演着一个重要的角色 在人类福祉中的作用，重要的是了解其生物合成和 监管。 维生素K的生物合成途径可概括如下： 2-琥珀酸基-6-羟基-2-丁二酸基-6-羟基-2 4-环己二烯-1-羧酸(SHCHC)-邻丁二酸 (OSB)-甲基-O-琥珀酰基苯甲酰辅酶A(OSB-CoA)-&gt；{1， 4-二羟基-2-萘甲酰辅酶A(DHNA-CoA)}-孟醇-1，4-二羟基-2-萘甲酸 酸(DHNA)-MENA-&gt；去甲基喹酮(DMK)-乌比--&gt； (MK)。 7个ORF(其中6个已被证明是菜籽酮生物合成基因) 以orf1O1、menF、Mend、MenH、MenB、MenC和Mene的顺序排列在一簇中。 所有基因的转录都是由单一的强启动子启动的 在厌氧条件下，检测到26个碱基5‘端的OfiOl。MENA基因 位于染色体上的89分钟处，并与一个未知的orf连锁 (Orf161)。 在这项研究中，我们建议1)确定orf101的作用；2)研究orf101 利用LacZ融合对MAN操纵子的调节；3)确定结构 建议的中间体(DHNA-CoA)；4)鉴定甲基转移酶 参与DMK--&GT；MK的转化，以及5)表征活性中心 OSB合酶的突变体，其三维结构最近被解决 就是我们。

DESCRIPITON (provided by applicant): Humans and animals cannot synthesize vitamin K (K). K dependent, hypoprothrombia is an important clinical problem under a number of conditions. The K requirement in human and animal nutrition is met by green plants and intestinal bacteria. Because K plays an important role in human well being, it is important to understand its biosynthesis and regulation. The vitamin K biosynthetic pathway may be summarized as follows: chorismate -menF--> isochorismate --menD--> 2-succinyl-6-hydroxy-2, 4-cyclohexadiene-1 -carboxylate (SHCHC) ---menC---->o-succinylbenzoic acid (OSB)-menE-> o-succinylbenzoyl-CoA (OSB-CoA) --menB-->{ 1, 4-dihydroxy-2-naphthoyl-CoA (DHNA-CoA)}---menH---> 1, 4-dihydroxy-2-naphthoic acid (DHNA) ---menA---> demethylmenaquinone (DMK) --- ubiE --> menaquinone (MK). Seven ORFs (six of which have been shown to be menaquinone biosynthetic genes) lie in a cluster in the order orf1O1, menF, menD, menH, menB, menC, and menE. Transcription of all the genes are initiated from a single strong promoter site, 26 bp 5' to orfiOl was detected under anaerobic conditions. The menA gene is located at 89 min on the chromosome and is linked to an unidentified orf (orf161). In this study, we propose 1) to determine the role of orf101; 2) to study the regulation of the men operon using lacZ fusions; 3) to determine the structure of a proposed intermediate (DHNA-CoA); 4) to identify the methyltranferase involved in the DMK-->MK conversion, and 5) to characterize the active site mutants of OSB synthase, whose three dimensional structure was recently solved by us.