A single amino acid substitution alters the vanillylamine synthesis activity of Capsicum pAMT

Kaori Sano; Saika Nakasato; Koji Nagata; Kenji Kobata

doi:10.1016/j.bbrc.2023.09.011

A single amino acid substitution alters the vanillylamine synthesis activity of Capsicum pAMT

Biochem Biophys Res Commun. 2023 Nov 5:680:86-92. doi: 10.1016/j.bbrc.2023.09.011. Epub 2023 Sep 10.

Authors

Kaori Sano¹, Saika Nakasato², Koji Nagata³, Kenji Kobata⁴

Affiliations

¹ Department of Chemistry, Faculty of Science, Josai University, Saitama, Japan. Electronic address: kaori-s@josai.ac.jp.
² Graduate School of Pharmaceutical Sciences, Josai University, Saitama, Japan.
³ Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
⁴ Graduate School of Pharmaceutical Sciences, Josai University, Saitama, Japan. Electronic address: kobata@josai.ac.jp.

PMID: 37729777
DOI: 10.1016/j.bbrc.2023.09.011

Abstract

Some Capsicum synthesize a unique pungent alkaloid called capsaicin in their fruits. In the synthetic pathway of capsaicin, vanillylamine is produced from vanillin in a reaction catalyzed by a putative aminotransferase (pAMT). Therefore, the capsaicinoids content in the fruits is thought to partially depend on the characteristics of pAMT. Comparing Yume-matsuri (yume), C. annuum variety, and red habanero (RH), C. chinense variety, the vanillylamine synthesis activity of the placental extract was higher in yume than in RH. When each recombinant pAMT (rpAMT) was generated using the Escherichia coli expression system and their activities were compared, yume rpAMT synthesized 14-fold more vanillylamine than RH rpAMT. The amino acid sequence of yume and RH pAMT deduced from the cDNAs revealed that only 7 of 459 residues differed. When a single amino acid residue-substituted rpAMT was generated in which the 56th amino acid was swapped with one other, the amount of vanillylamine synthesis of yume and RH rpAMTs was inverted. Furthermore, it was suggested that the 56th amino acid contributed to the affinity for the coenzyme pyridoxal phosphate. Differences in the vanillylamine synthesis activity of pAMT may also lead to differences in the amount of capsaicin synthesis that accumulates in the fruit. Since capsaicin is a compound with commercial value, this finding may provide new insights into the creation of a variety that can synthesize more capsaicin.

Keywords: Capsaicin; Capsicum; Putative aminotransferase (pAMT); Single amino acid substitution; Vanillylamine.