Brown Christian, Szpryngiel Scarlett, Kuang Guanglin, Srivastava Vaibhav, Ye Weihua, McKee Lauren S, Tu Yaoquan, Mäler Lena, Bulone Vincent
Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden.
Department of Biochemistry and Biophysics, The Arrhenius Laboratory, Stockholm University, Sweden.
FEBS J. 2016 Aug;283(16):3072-88. doi: 10.1111/febs.13794. Epub 2016 Jul 22.
Chitin synthases (Chs) are responsible for the synthesis of chitin, a key structural cell wall polysaccharide in many organisms. They are essential for growth in certain oomycete species, some of which are pathogenic to diverse higher organisms. Recently, a microtubule interacting and trafficking (MIT) domain, which is not found in any fungal Chs, has been identified in some oomycete Chs proteins. Based on experimental data relating to the binding specificity of other eukaryotic MIT domains, there was speculation that this domain may be involved in the intracellular trafficking of Chs proteins. However, there is currently no evidence for this or any other function for the MIT domain in these enzymes. To attempt to elucidate their function, MIT domains from two Chs enzymes from the oomycete Saprolegnia monoica were cloned, expressed, and characterized. Both were shown to interact strongly with the plasma membrane component, phosphatidic acid, and to have additional putative interactions with proteins thought to be involved in protein transport and localization. Aiding our understanding of these data, the structure of the first MIT domain from a carbohydrate-active enzyme (MIT1) was solved by NMR, and a model structure of a second MIT domain (MIT2) was built by homology modeling. Our results suggest a potential function for these MIT domains in the intracellular transport and/or regulation of Chs enzymes in the oomycetes.
Structural data are available in the Biological Magnetic Resonance Bank (BMRB) database under the accession number 19987 and the PDB database under the accession number 2MPK.
几丁质合酶（Chs）负责几丁质的合成，几丁质是许多生物体中关键的细胞壁结构多糖。它们对于某些卵菌物种的生长至关重要，其中一些对多种高等生物具有致病性。最近，在一些卵菌Chs蛋白中发现了一种微管相互作用与运输（MIT）结构域，而在任何真菌Chs中都未发现该结构域。基于与其他真核生物MIT结构域结合特异性相关的实验数据，有人推测该结构域可能参与Chs蛋白的细胞内运输。然而，目前尚无证据证明该MIT结构域在这些酶中具有此功能或任何其他功能。为了试图阐明它们的功能，克隆、表达并表征了来自卵菌绵霉的两种Chs酶的MIT结构域。结果表明，这两种结构域都与质膜成分磷脂酸强烈相互作用，并与被认为参与蛋白质运输和定位的蛋白质存在其他假定的相互作用。为帮助我们理解这些数据，通过核磁共振解析了一种碳水化合物活性酶的首个MIT结构域（MIT1）的结构，并通过同源建模构建了第二个MIT结构域（MIT2）的模型结构。我们的结果表明这些MIT结构域在卵菌中Chs酶的细胞内运输和/或调节中具有潜在功能。
结构数据可在生物磁共振数据库（BMRB）中获取，登录号为19987，在蛋白质数据银行（PDB）数据库中获取，登录号为2MPK。
