Carboxyspermidine decarboxylase of the prominent intestinal microbiota species Bacteroides thetaiotaomicron is required for spermidine biosynthesis and contributes to normal growth.
Recent studies have indicated that polyamines produced by gut microbes significantly influence host health; however, little is known about the microbial polyamine biosynthetic pathway except for that in Escherichia coli, a minor component of the gastrointestinal microbiota. Here, we investigated the polyamine biosynthetic ability of Bacteroides thetaiotaomicron, a predominant gastrointestinal bacterial species in humans. High-performance liquid chromatography analysis revealed that B. thetaiotaomicron cultured in polyamine-free minimal medium accumulated spermidine intracellularly at least during the mid-log and stationary phases. Deletion of the gene encoding a putative carboxyspermidine decarboxylase (casdc), which converts carboxyspermidine to spermidine, resulted in the depletion of spermidine and loss of decarboxylase activity in B. thetaiotaomicron. The Δcasdc strain also showed growth defects in polyamine-free growth medium. The complemented Δcasdc strain restored the spermidine biosynthetic ability, decarboxylase activity, and growth. These results indicate that carboxyspermidine decarboxylase is essential for synthesizing spermidine in B. thetaiotaomicron and contributes to the growth of this species.
Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan.
Mikiyasu
M
Sakanaka
Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan.
Yuta
Y
Sugiyama
Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan.
Aya
A
Kitakata
Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan.|Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan.
Takane
T
Katayama
Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan. kuri711@ishikawa-pu.ac.jp.
Shin
S
Kurihara
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000070077:Bacteroides thetaiotaomicron / Q000235:genetics / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D000069196:Gastrointestinal Microbiome; D013095:Spermidine / Q000096:biosynthesis*
D001426:Bacterial Proteins; D002262:Carboxy-Lyases; D013095:Spermidine
Bacteroides; Carboxyspermidine; Carboxyspermidine decarboxylase; Gastrointestinal microbiota; Polyamine; Spermidine