Chan Chio Mui, Huang Raven H
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Arch Biochem Biophys. 2009 Sep;489(1-2):15-9. doi: 10.1016/j.abb.2009.07.023. Epub 2009 Aug 5.
Pseudouridine (Psi) is formed through isomerization of uridine (U) catalyzed by a class of enzymes called pseudouridine synthases (PsiS). TruD is the fifth family of PsiS. Studies of the first four families (TruA, TruB, RsuA, and RluA) of PsiS reveal a conserved Asp and Tyr are critical for catalysis. However, in TruD family, the tyrosine is not conserved. In this study, we measured the enzymatic parameters for TruD in Escherichia coli, and carried out enzymatic assays for a series of single, double, and triple TruD mutants. Our studies indicate that a Glu, strictly conserved in only TruD family is likely to be the general base in TruD. We also proposed a possible distinct mechanism of TruD-catalyzed Psi formation compared to the first four families.
假尿苷（Ψ）是由一类称为假尿苷合酶（PsiS）的酶催化尿苷（U）异构化形成的。TruD是PsiS的第五个家族。对PsiS的前四个家族（TruA、TruB、RsuA和RluA）的研究表明，保守的天冬氨酸和酪氨酸对催化作用至关重要。然而，在TruD家族中，酪氨酸并不保守。在本研究中，我们测定了大肠杆菌中TruD的酶学参数，并对一系列单、双、三TruD突变体进行了酶活性测定。我们的研究表明，仅在TruD家族中严格保守的谷氨酸可能是TruD中的通用碱基。我们还提出了一种与前四个家族相比，TruD催化Ψ形成的可能不同机制。
