ABSTRACT
Through the use of genetic, enzymatic, metabolomic, and structural analyses, we have discovered the catabolic pathway for proline betaine, an osmoprotectant, in
Paracoccus denitrificans
and
Rhodobacter sphaeroides
. Genetic and enzymatic analyses showed that several of the key enzymes of the hydroxyproline betaine degradation pathway also function in proline betaine degradation. Metabolomic analyses detected each of the metabolic intermediates of the pathway. The proline betaine catabolic pathway was repressed by osmotic stress and cold stress, and a regulatory transcription factor was identified. We also report crystal structure complexes of the
P. denitrificans
HpbD hydroxyproline betaine epimerase/proline betaine racemase with
l
-proline betaine and
cis
-hydroxyproline betaine.
IMPORTANCE
At least half of the extant protein annotations are incorrect, and the errors propagate as the number of genome sequences increases exponentially. A large-scale, multidisciplinary sequence- and structure-based strategy for functional assignment of bacterial enzymes of unknown function has demonstrated the pathway for catabolism of the osmoprotectant proline betaine.
摘要
通过使用
基因、酶、代谢组和结构分析,我们发现了脯
氨酸
甜菜碱(一种渗透保护剂)在
脱硝副球菌
和
的分解途径。
.遗传学和酶学分析表明,羟脯
氨酸
甜菜碱降解途径中的几种关键酶也在脯
氨酸
甜菜碱降解中发挥作用。代谢组分析检测到了该途径的每个代谢中间产物。脯
氨酸
甜菜碱分解途径受到渗透胁迫和冷胁迫的抑制,并确定了一个调控转录因子。我们还报告了
HpbD
HpbD 羟脯
氨酸
甜菜碱外
氨酶/脯
氨酸
甜菜碱消旋酶与
l
-脯
氨酸
甜菜碱和
顺式
-羟脯
氨酸
甜菜碱。
重要意义
现存蛋白质注释中至少有一半是不正确的,而且随着
基因组序列数量的指数级增长,错误也在不断扩大。一种基于序列和结构的大规模、多学科的细菌未知功能酶功能分配策略证明了渗透保护剂脯
氨酸
甜菜碱的分解途径。