Pichu Sivakamasundari, Ribeiro José M C, Mather Thomas N
Center for Vector-Borne Disease, University of Rhode Island, Kingston, RI 02881, USA.
Biochem Biophys Res Commun. 2009 Dec 18;390(3):511-5. doi: 10.1016/j.bbrc.2009.09.127. Epub 2009 Oct 21.
A novel antimicrobial peptide was isolated from the saliva of the Lyme disease tick vector, Ixodes scapularis, henceforth designated as ISAMP (I. scapularis Antimicrobial Peptide). ISAMP was purified using a sequential method including ultra filtration, gel filtration and reverse-phase high performance liquid chromatography. The purified peak had a molecular weight of 5.3kDa by MALDI/TOF-MS and its amino acid sequence, determined by Edman degradation was PDxGxPxxVKAGRxPxxSI. A BLASTP search revealed that the protein is a putative 5.3kDa secreted protein (AAM93656) from I. scapularis. The predicted protein is composed of 69 amino acids with no conserved domain motifs. Purified ISAMP was found to have antimicrobial activities against bacteria. Gene expression studies were carried out to observe ISAMP expression in different tick tissues. RT-PCR results indicated that the gene was expressed in hemocytes, fat body and salivary gland but virtually no expression was observed in the midgut. ISAMP is only similar to other Ixodid tick proteins, thus it is a member of a unique family.
从莱姆病蜱虫媒介肩突硬蜱的唾液中分离出一种新型抗菌肽，此后将其命名为ISAMP（肩突硬蜱抗菌肽）。采用包括超滤、凝胶过滤和反相高效液相色谱在内的顺序方法对ISAMP进行纯化。通过基质辅助激光解吸电离飞行时间质谱（MALDI/TOF-MS）测定，纯化峰的分子量为5.3kDa，通过埃德曼降解法确定其氨基酸序列为PDxGxPxxVKAGRxPxxSI。BLASTP搜索显示，该蛋白是肩突硬蜱一种假定的5.3kDa分泌蛋白（AAM93656）。预测的蛋白由69个氨基酸组成，没有保守的结构域基序。发现纯化的ISAMP对细菌具有抗菌活性。进行了基因表达研究以观察ISAMP在不同蜱虫组织中的表达。逆转录聚合酶链反应（RT-PCR）结果表明，该基因在血细胞、脂肪体和唾液腺中表达，但在中肠中几乎未观察到表达。ISAMP仅与其他硬蜱蛋白相似，因此它是一个独特家族的成员。
