Da Silva Pedro, Jouvensal Laurence, Lamberty Mireille, Bulet Philippe, Caille Anita, Vovelle Françoise
Centre de Biophysique Moléculaire, UPR 4301 CNRS affiliated at Orléans University, 45071 Orléans cedex 2, France.
Protein Sci. 2003 Mar;12(3):438-46. doi: 10.1110/ps.0228303.
The solution structure of termicin from hemocytes of the termite Pseudacanthotermes spiniger was determined by proton two-dimensional nuclear magnetic resonance spectroscopy and molecular modeling techniques. Termicin is a cysteine-rich antifungal peptide also exhibiting a weak antibacterial activity. The global fold of termicin consists of an alpha-helical segment (Phe4-Gln14) and a two-stranded (Phe19-Asp25 and Gln28-Phe33) antiparallel beta-sheet forming a "cysteine stabilized alphabeta motif" (CSalphabeta) also found in antibacterial and antifungal defensins from insects and from plants. Interestingly, termicin shares more structural similarities with the antibacterial insect defensins and with MGD-1, a mussel defensin, than with the insect antifungal defensins such as drosomycin and heliomicin. These structural comparisons suggest that global fold alone does not explain the difference between antifungals and antibacterials. The antifungal properties of termicin may be related to its marked hydrophobicity and its amphipatic structure as compared to the antibacterial defensins. [SWISS-PROT accession number: Termicin (P82321); PDB accession number: 1MM0.]
通过质子二维核磁共振光谱和分子建模技术确定了来自刺白蚁血细胞的白蚁杀菌肽的溶液结构。白蚁杀菌肽是一种富含半胱氨酸的抗真菌肽，也表现出较弱的抗菌活性。白蚁杀菌肽的整体折叠由一个α-螺旋片段（Phe4-Gln14）和一个双链（Phe19-Asp25和Gln28-Phe33）反平行β-折叠组成，形成了一个“半胱氨酸稳定的αβ基序”（CSαβ），在昆虫和植物的抗菌和抗真菌防御素中也有发现。有趣的是，与昆虫抗真菌防御素如果蝇抗菌肽和日蝇抗菌肽相比，白蚁杀菌肽与抗菌昆虫防御素以及贻贝防御素MGD-1具有更多的结构相似性。这些结构比较表明，仅整体折叠并不能解释抗真菌和抗菌防御素之间的差异。与抗菌防御素相比，白蚁杀菌肽的抗真菌特性可能与其显著的疏水性和两亲结构有关。[SWISS-PROT登录号：白蚁杀菌肽（P82321）；PDB登录号：1MM0。]
