Nakajima Masahiro, Nishimoto Mamoru, Kitaoka Motomitsu
National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
Appl Microbiol Biotechnol. 2009 May;83(1):109-15. doi: 10.1007/s00253-008-1838-y. Epub 2009 Jan 9.
Homologs of the beta-1,3-galactosyl-N-acetylhexosamine phosphorylase (GalHexNAcP) gene (gnpA) were cloned from the genomic DNA of Propionibacterium acnes JCM6425 and P. acnes JCM6473, showing 99.9% and 97.9% nucleotide sequence identity, respectively, with the ppa0083 gene from the genome-sequenced P. acnes KPA171202. No gnpA gene was detected in the genomic DNA of type strain P. acnes ATCC25746. The recombinant enzyme from P. acnes JCM6425 (GnpA) showed approximately 70 times higher specific activity of phosphorolysis on galacto-N-biose (Galbeta1-->3GalNAc, GNB) than that on lacto-N-biose I (Galbeta1-->3GlcNAc). K (m) value for GnpA on GNB was high, but GnpA did not exhibit activity on any derivatives of GNB examined. These results indicate that GnpA is GalHexNAcP which should be classified as galacto-N-biose phosphorylase. The large k (cat) value of GnpA on GalNAc suggests that GnpA would be a useful catalyst for the synthesis of GNB.
从痤疮丙酸杆菌JCM6425和痤疮丙酸杆菌JCM6473的基因组DNA中克隆出β-1,3-半乳糖基-N-乙酰己糖胺磷酸化酶（GalHexNAcP）基因（gnpA）的同源物，它们与来自基因组测序的痤疮丙酸杆菌KPA171202的ppa0083基因的核苷酸序列同一性分别为99.9%和97.9%。在痤疮丙酸杆菌ATCC25746模式菌株的基因组DNA中未检测到gnpA基因。来自痤疮丙酸杆菌JCM6425的重组酶（GnpA）对半乳糖-N-二糖（Galβ1→3GalNAc，GNB）的磷酸解比活性比对乳糖-N-二糖I（Galβ1→3GlcNAc）高约70倍。GnpA对GNB的K（m）值较高，但GnpA对所检测的任何GNB衍生物均无活性。这些结果表明GnpA是GalHexNAcP，应归类为半乳糖-N-二糖磷酸化酶。GnpA对GalNAc的大k（cat）值表明GnpA可能是合成GNB的有用催化剂。
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