Rehm Bernd H A
Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Curr Issues Mol Biol. 2007 Jan;9(1):41-62.
Biopolyester (PHAs = polyhydroxyalkanoates) composed of hydroxy fatty acids represent a rather complex class of storage polymers synthesized by various eubacteria and archaea and are deposited as water-insoluble cytoplasmic nano-sized inclusions. These spherical shell-core particles are composed of a polyester core surrounded by phospholipids and proteins. The key enzymes of polyester biosynthesis and polyester particle formation are the polyester synthases, which catalyze the enantio-selective polymerization of (R)-hydroxyacyl-CoA thioesters to polyesters. Various metabolic routes have been identified and established in bacteria to provide substrate for polyester synthases. The role of the polyester synthases in morphogenesis and presumably self-assembly of these natural polyester particles will be described. Although not essential for particle formation, non-covalently attached proteins, the so-called phasins, can be found at the particle surface and are considered as structural proteins. A multiple alignment of 88 polyester synthases indicated an identity varying from 8% to 96% with eight strictly conserved amino acid residues. Protein engineering of polyester synthases and phasins was used to functionalize the polyester particle surface. The current knowledge enables the microbial and biocatalytic production of particles with controlled size, polyester core composition and surface functionality, which suggested numerous potential applications of these biocompatible and biodegradable nanostructures particularly in the medical field.
由羟基脂肪酸组成的生物聚酯（PHA = 聚羟基脂肪酸酯）是一类相当复杂的储存聚合物，由各种真细菌和古细菌合成，并以水不溶性的细胞质纳米级内含物形式沉积。这些球形的壳核颗粒由一个聚酯核心和围绕其的磷脂及蛋白质组成。聚酯生物合成和聚酯颗粒形成的关键酶是聚酯合酶，它催化（R）-羟基酰基辅酶A硫酯对映选择性聚合成聚酯。在细菌中已鉴定并确立了各种代谢途径，以为聚酯合酶提供底物。将描述聚酯合酶在这些天然聚酯颗粒的形态发生以及可能的自组装中的作用。虽然对于颗粒形成不是必需的，但在颗粒表面可以发现非共价连接的蛋白质，即所谓的phasins，它们被视为结构蛋白。88种聚酯合酶的多重比对表明，其同一性在8%至96%之间，有八个严格保守的氨基酸残基。聚酯合酶和phasins的蛋白质工程被用于使聚酯颗粒表面功能化。目前的知识使得能够通过微生物和生物催化生产具有可控尺寸、聚酯核心组成和表面功能的颗粒，这表明这些生物相容性和可生物降解的纳米结构有许多潜在应用，特别是在医学领域。
