Department of Microbial Interactions, Institute of Microbiology, Friedrich Schiller University, Jena, Germany.
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, WI, USA.
FEBS Lett. 2019 Nov;593(21):3040-3053. doi: 10.1002/1873-3468.13543. Epub 2019 Jul 30.
Structural diversity of natural cobamides (Cbas, B vitamers) is limited to the nucleotide loop. The loop is connected to the cobalt-containing corrin ring via an (R)-1-aminopropan-2-ol O-2-phosphate (AP-P) linker moiety. AP-P is produced by the l-threonine O-3-phosphate (l-Thr-P) decarboxylase CobD. Here, the CobD homolog SMUL_1544 of the organohalide-respiring epsilonproteobacterium Sulfurospirillum multivorans was characterized as a decarboxylase that produces ethanolamine O-phosphate (EA-P) from l-serine O-phosphate (l-Ser-P). EA-P is assumed to serve as precursor of the linker moiety of norcobamides that function as cofactors in the respiratory reductive dehalogenase. SMUL_1544 (SmCobD) is a pyridoxal-5'-phosphate (PLP)-containing enzyme. The structural analysis of the SmCobD apoprotein combined with the characterization of truncated mutant proteins uncovered a role of the SmCobD N-terminus in efficient l-Ser-P conversion.
天然钴胺素（Cbas，维生素 B 族）的结构多样性仅限于核苷酸环。该环通过（R）-1-氨基-2-丙醇 O-2-磷酸（AP-P）连接部分与含钴的咕啉环相连。AP-P 是由 l-苏氨酸 O-3-磷酸（l-Thr-P）脱羧酶 CobD 产生的。在这里，有机卤化物呼吸型 ε-变形菌 Sulfurospirillum multivorans 的 CobD 同源物 SMUL_1544 被鉴定为一种脱羧酶，它可将 l-丝氨酸 O-磷酸（l-Ser-P）转化为乙醇胺 O-磷酸（EA-P）。EA-P 被认为是 norcobamides 连接部分的前体，norcobamides 在呼吸还原脱卤酶中作为辅因子发挥作用。SMUL_1544（SmCobD）是一种含有吡哆醛-5'-磷酸（PLP）的酶。SmCobD 脱辅基蛋白的结构分析结合截短突变蛋白的特性，揭示了 SmCobD N 端在有效 l-Ser-P 转化中的作用。
