Casteels-Josson K, Capaci T, Casteels P, Tempst P
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY.
EMBO J. 1993 Apr;12(4):1569-78. doi: 10.1002/j.1460-2075.1993.tb05801.x.
Apidaecins are the most prominent components of the honeybee humoral defense against microbial invasion. Our analysis of cDNA clones indicated that up to 12 of these short peptides (2 kDa) can be generated by processing of single precursor proteins; different isoforms are hereby linked in one promolecule. Assembly of the multipeptide precursors and the putative three-step maturation are strongly reminiscent of yeast alpha-mating factor. Bioactive apidaecins are flanked by the two 'processing' sequences, EAEPEAEP (or variants) and RR; joined together, they form a single unit that is repeated numerous times. The number of such repeats is variable and was reflected in the observed diversity of transcript lengths. Each such transcript is likely to be encoded by a different gene, forming a tight gene cluster. While transcriptional activation upon bacterial challenge is not exceptionally fast, the multigene and multipeptide precursor nature of the apidaecin genetic information allows for amplification of the response, resulting in a real overproduction of peptide antibiotic. Enhanced efficiency of the 'immune' response to bacterial infection through such a mechanism is, to our knowledge, unique among insects.
蜜蜂抗菌肽是蜜蜂体液防御微生物入侵的最主要成分。我们对cDNA克隆的分析表明，这些短肽（2 kDa）中多达12种可通过单一前体蛋白的加工产生；不同的异构体由此连接在一个前体分子中。多肽前体的组装和假定的三步成熟过程强烈让人联想到酵母α-交配因子。具有生物活性的蜜蜂抗菌肽两侧是两个“加工”序列，EAEPEAEP（或变体）和RR；它们连接在一起，形成一个重复多次的单一单元。这种重复的数量是可变的，并反映在观察到的转录本长度的多样性中。每个这样的转录本可能由不同的基因编码，形成一个紧密的基因簇。虽然细菌攻击后的转录激活不是特别快，但蜜蜂抗菌肽遗传信息的多基因和多肽前体性质允许反应放大，导致肽抗生素的真正过量产生。据我们所知，通过这种机制增强对细菌感染的“免疫”反应效率在昆虫中是独一无二的。
