Genome-wide identification and functional characterization of alpha-amylase genes in Litopenaeus vannamei

Abstract

Alpha-amylase is a key enzyme involved in carbohydrate hydrolysis and food digestion in animals. However, its molecular characteristics and functions remain poorly understood in the economically important Pacific white shrimp, Litopenaeus vannamei . Through comparative genomic analysis, this study revealed that the α-amylase ( Amy ) gene family has undergone an expansion in arthropods, particularly crustaceans, while retaining highly conserved catalytic domains. Six Amy genes were identified in L. vannamei . Their expression patterns across tissues and developmental stages revealed predominant transcription in the hepatopancreas, with significant upregulation during periods of high energy demand, such as zoeal feeding and pre-molting. Among these genes, Lv-Amy (XP_027225605.1) exhibited the highest expression level. Quantitative real-time PCR (qPCR) and fluorescence in situ hybridization (F IS H) further characterized the tissue distribution and cellular localization of Lv-Amy . Structurally, Lv -Amy displays a typical (β/α)₈ TIM barrel conformation and two conserved calcium-binding sites. The recombinant Lv -Amy protein was produced in an E. coli expression system and its enzymatic properties were characterized. Maximal activity of the recombinant Lv -Amy protein was observed at pH 7.5 and 25°C, while activity remained above 50% of the maximum within pH 7.0–8.0 and 20–45°C, indicating that Lv- Amy can function efficiently under environmental conditions characteristic of the tropical marine habitat of L. vannamei . In summary, this study provides new insights into the molecular characteristics and functions of α-amylase in L. vannamei , suggesting that Lv-Amy plays an important role in digestion and offering a reference of stage-specific nutritional formulation for this species.