Evolution of a Histidinol Dehydrogenase (Hdh2) Pseudogene in wheat-biotype Phaeosphaeria nodorum

小麥葉枯病菌Phaeosphaeria nodorum 組胺酸脫氫酵素僞基因之演化分析

王智立(Chih-Li Wang) ； 林盈宏(Ying-Hong Lin) ； 邱燕欣(Ericka Y. H. Chiu) ； 翁溥(Peter P. Ueng)

《植物病理學會刊》 17卷3期 (2008/09) Pp. 221-232

https://doi.org/10.6649/PPB.200809_17(3).0005

摘要

組胺酸脫氫酵素(L-histidinol: NAD(上標 +)dehydrogenase: HDH; EC 1.1.1.23)是高等真菌合成三功能－組胺酸(tri-funcitional histidine, his)的三種生合成酵素之一，於生合成組胺酸之最後兩個步驟中扮演催化的角色。本研究從小麥葉枯病菌(Wheat-biotype Phaeosphaeria nodorum, PM-w)與從波蘭祼麥分離之Phaeosphaeria sp. (P-rye)上鑑定出一單套之組胺酸脫氫酵素基因(Hdh2)，但是此Hdh2基因並不存在於大麥葉枯病菌(barley-biotype P. nodorum, PN-b)菌株、燕麥殼針孢病菌P. avenaria f. sp. avenaria (Paa)、麥类殼多胞斑點病菌(P. avenaria f. sp. triticea, Pat1、Pat2、Pat3)三群菌株，以及從達利雀稗(dallies grass, Paspalum dilatatum Poir)分離之Phaeosphaeria sp.菌株之中。由於PN-w Sn37-1的Hdh2基因於基礎培養基(Minimal media)與豐富培養基(Rich medium)上無法表現，得知Hdh2爲一僞基因。另外與受質結合以及2價鋅之結合配體(Zn(上標 2+) ligand)形成具重要性且與組胺氫酵素之活性有關之大部分胺基酸，完整保留於Hdh2蛋白中。藉由胺基酸序列推演其菌株間親緣性分析得知，在真菌HIS蛋白的Hdh1胺基酸序列中，其組胺酸脫氫酵素之胺基酸位置，包括C-116及C-153皆爲半胱胺酸(cysteine, C)，因而被分群至細菌群。則3個Aspergillus屬與2個Phaeosphaeria屬之Hdh2蛋白，在該組胺酸脫氫酵素的大部分分析中，C-116的位置爲白胺酸(leucine, L)，而C-153的位置全爲纈胺酸(valine, V)，因此被分群至不同的細菌群。本文亦針對Aspergillus與Phaeosphaeria屬之Hdh2之基因演化進行討論。

關鍵字

小麥葉枯病菌 ； 小麥穎枯病 ； 組胺酸脫氫酵素 ； 僞基因 ； 親緣分析

並列摘要

Histidinol dehydrogenase (L-histidinol: NAD(superscript +) oxidoreductase. HDH; EC 1.1.1.23) is one of three biosynthetic enzymes encoded by the tri-functional histidine biosynthesis (his) gene in high fungi, which catalyzes the last two steps of the histidine biosynthesis. A single histidinol dehydrogenase (Hdh2) gene was identified in a heat-biotype Phaeosphaeria nodorum (PN-w) and Phaeosphaeria sp, from Polish rye (P-rye). The Hdh2 gene was not present in barley-biotype P. nodorum (PN-b), P. avenaria f. sp. avenaria (Paa), 3 groups of P. avenaria f. sp. triticea (Pst1, Pat2 and Pat3) and Phaeosphaeria sp. front dallis grass (Paspalum dilatatum Poir.). Since the Hdh2 gene in PN-w Sn37-1 isolate was not expressed in the cultures grown in rich and minimal media, it was a pseudo-gene. Most of the amino acids important for substrate binding and Zn(superscript 2+) ligand formation for histidinol dehydrogenase enzymatic activity activity well conserved in the Hdh2 protein. In phylogenetic analysis based on the deduced peptide sequences, the Hdh1 peptides in the HIS proteins of the fungi were grouped witlt the bacteria which had cysteine (C) at both C-116 and C-153 positions in histidinol dehydrogenases. The Hdh2 proteins from3 Aspergillus and 2 Phaeosphaeria species were grouped with the bacteria, which had mostly leucine (L) at C-116 and all with valine (V) at C-153 positions in histidinol dehydrogenases. Evolution of the Hdh2 genes the Phaeosphaeria and Aspergillus species acre discussed.

並列關鍵字

Phaeosphaeria nodorum ； wheat glume blotch ； histidinol dehydrogenase ； pseudo-gene ； phylogenetic analysis