张会 单雷 李新国 郭峰 孟静静 万书波 彭振英

摘要：酰基-ACP硫酯酶（fatty acyl-ACP thioesterase，FAT）是控制植物种子油脂合成的关键酶，根据其氨基酸序列和底物特异性不同可分为FATA和FATB两类。为了更深入了解花生FAT（AhFAT）的特点与功能，本研究对AhFAT家族基因进行了全基因组生物信息学分析。在花生基因组中共有20个FAT基因，不均匀分布在2个基因组的12条染色体上。20个AhFATs可以分为AhFATA和AhFATB两个亚家族，AhFATA亚家族有2个基因，AhFATB亚家族有18个基因。AhFATA家族基因具有6或8个外显子，AhFATB家族基因结构较为复杂，外显子数目5～8个；AhFATs都不具有跨膜结构域但是都具有保守的Acyl-ACP_TE结构域。对AhFAT家族基因进行可变剪接分析，发现只有少数发生了可变剪接，且具有组织特异性。对AhFATs表达模式分析的结果显示，AhFATAs和AhFATBs都在种子发育后期表达量较高。

关键词：花生；酰基载体蛋白硫酯酶（FAT）；可变剪接；表达模式

中图分类号：S565.2：Q7文献标识号：A文章编号：1001-4942（2018）06-0019-08

Abstract Fatty acyl-ACP thioesterase （FAT） is the key enzyme regulating the synthesis of plant seed oil. According to the amino acid sequence and substrate specificity， FAT is divided into FATA and FATB subfamily. In order to better understand the characteristics of AhFAT gene family， the bioinformatics analysis was carried out. There were 20 AhFAT genes in the peanut genome， which heterogeneously distributed on 12 chromosomes in the two genomes. The twenty AhFAT genes could be divided into AhFATA and AhFATB subfamily， which had 2 and 18 members respectively. The AhFATA subfamily owned 6 or 8 exons， and the AhFATB subfamily had complex gene structures with 5～8 exons. None of the AhFATs had transmembrane domains， but they all owned the conserved Acyl-ACP_TE domain. The alternative splicing analysis of AhFAT gene family revealed that only a few AhFATs undergone alternative splicing and they had different splicing types in different tissues. The AhFATs expression pattern analysis results showed that both AhFATAs and AhFATBs expressed at higher levels in the later stage of seed development.

Keywords Peanut； Fatty acyl-ACP thioesterase （FAT）； Alternative splicing； Expression pattern

在高等植物中，脂肪酸生物合成是由位于质体中的Ⅱ型脂肪酸合成酶催化完成的[1]。该反应包括丙二酸单酰辅酶A与酰基-ACP衍生物的聚合反应，使酰基碳链以每个循环增加两个碳单位进行延伸[2]。酰基-ACP硫酯酶（fatty acyl-ACP thioesterase， FAT）终止脂肪酸合成，水解酰基和ACP之间的硫酯键，释放出游离脂肪酸和ACP[3-6]。脂肪酸被运送到细胞质中进一步酯化形成脂酰-CoA，然后在内质网上进行脂肪酸链的延长和脱饱和、磷脂和甘油三酯的合成等代谢[7，8]。FAT的特异性在很大程度上决定了大多数植物脂肪酸链的长度和不饱和度[9]。

FAT是由核基因编码的质体靶向的可溶性酶[7]。……