Perez Rodney H, Sugino Haruki, Ishibashi Naoki, Zendo Takeshi, Wilaipun Pongtep, Leelawatcharamas Vichien, Nakayama Jiro, Sonomoto Kenji
Laboratory of Microbial Technology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka 812-8581, Japan.
Present address: National Institute for Molecular Biology and Biotechnology (BIOTECH), University of the Philippines Los Baños, Laguna 4031, Philippines.
Microbiology (Reading). 2017 Apr;163(4):431-441. doi: 10.1099/mic.0.000435. Epub 2017 Apr 12.
Enterocin NKR-5-3B (Ent53B) is a 64-residue novel circular bacteriocin synthesized from an 87-residue prepeptide. Albeit through a still unknown mechanism, the EnkB1234 biosynthetic enzyme complex processes the prepeptide to yield its mature active, circular form. To gain insights into the key region/residue that plays a role in Ent53 maturation, several mutations near the cleavage site on the precursor peptide were generated. The interaction of the precursor peptide and EnkB1234 appeared to be hydrophobic in nature. At the Leu1 position, only mutations with helix structure-promoting hydrophobic residues (Ala, Ile, Val or Phe) were able to yield the mature Ent53B derivative. In this study, we also highlight the possible conformation-stabilizing role of the Ent53B leader peptide on the precursor peptide for its interaction with its biosynthetic enzyme complex. Any truncations of the leader peptide moiety interfered in the processing of the prepeptide. However, when propeptides of other circular bacteriocins (circularin A, leucocyclicin Q or lactocyclicin Q) were cloned at the C-terminus of the leader peptide, EnkB1234 could not process them to yield a mature bacteriocin. Taken together, these findings offer new perspectives in our understanding of the possible molecular mechanism of the biosynthesis of this circular bacteriocin. These new perspectives will help advance our current understanding to eventually elucidate circular bacteriocin biosynthesis. Understanding the biosynthetic mechanism of circular bacteriocins will materialize their application potential.
肠球菌素NKR-5-3B（Ent53B）是一种由87个氨基酸的前体肽合成的含64个氨基酸的新型环状细菌素。尽管其机制尚不清楚，但EnkB1234生物合成酶复合物可加工前体肽以产生其成熟的活性环状形式。为了深入了解在Ent53成熟过程中起作用的关键区域/残基，在前体肽切割位点附近产生了几个突变。前体肽与EnkB1234的相互作用似乎本质上是疏水性的。在Leu1位置，只有具有促进螺旋结构的疏水残基（Ala、Ile、Val或Phe）的突变才能产生成熟的Ent53B衍生物。在本研究中，我们还强调了Ent53B前导肽对前体肽与生物合成酶复合物相互作用可能具有的构象稳定作用。前导肽部分的任何截断都会干扰前体肽的加工。然而，当其他环状细菌素（环杆菌素A、白细胞环菌素Q或乳环菌素Q）的前肽克隆在前导肽的C末端时，EnkB1234无法加工它们以产生成熟的细菌素。综上所述，这些发现为我们理解这种环状细菌素生物合成的可能分子机制提供了新的视角。这些新视角将有助于推动我们目前的理解，最终阐明环状细菌素的生物合成。了解环状细菌素的生物合成机制将实现它们的应用潜力。
