Abdubeck, Polat, Chen, Connie, Feuerhelm, Julie, Grant, Joanna, Klock, Heath, Knuth, Mark, Nigoghossian, Edward, Okach, Linda, Puckett, Christina, Wooten, Tiffany, Zhou, Jiadong, Lesley, Scott, Stolz, Barbara and Xu, Qingping (2010) GNF ID 100603: Crystal structure of Haemophilus influenzae prephenate dehydrogenase suggests unique features of bifunctional TyrA enzymes. Acta F.

Abstract

Crystal structure of the prephenate dehydrogenase component (HinfPDH) of the bi-functional
Haemophilus influenza TyrA reveals unique structural differences between bi-functional and monofunctional
TyrA enzymes.
Chorismate mutase / prephenate dehydrogenase from Haemophilus influenzae Rd KW20 is a bifunctional
enzyme that catalyzes the rearrangement of chorismate to prephenate and the NAD(P)+-
dependent oxidative decarboxylation of prephenate to 4-hydroxyphenyl pyruvate in tyrosine
biosynthesis. The crystal structure of the prephenate dehydrogenase component (HinfPDH) of the TyrA
protein from Haemophilus influenzae Rd KW20, in complex with inhibitor tyrosine and cofactor NAD+,
has been determined to 2.0 Å resolution. HinfPDH is a dimeric enzyme, with each monomer consisting
of an N-terminal, α/β dinucleotide-binding domain and a C-terminal, α-helical dimerization domain.
The structure reveals key active site residues at the domain interface, including His200, Arg297 and
Ser179 that are involved in catalysis and substrate binding and are highly conserved in TyrA proteins
from all three kingdoms of life. Tyrosine is bound directly at the catalytic site, suggesting that it is a
competitive inhibitor of HinfPDH. Comparisons with its structural homologues reveal important
differences around the active site, including the absence of an α−β motif in HinfPDH that is present in
other TyrA proteins, such as Synechocystis sp. arogenate dehydrogenase. Residues from this motif are
involved in discrimination of NADP+ and NAD+. The loop between β5 and β6 in the N-terminal domain
is much shorter in HinfPDH and an extra helix is present at the C-terminus. Furthermore, HinfPDH
adopts a more closed conformation, compared to TyrA proteins that do not have tyrosine bound. This
conformational change brings the substrate, cofactor and active site residues into close proximity for
catalysis. An ionic network consisting of Arg297 (a key residue for tyrosine binding), a water molecule,Asp206 (from the loop between β5 and β6) and Arg365’ (from the extra C-terminal helix of the
adjacent monomer) is observed, which might be involved in gating the active site.

Item Type:	Article
Additional Information:	B. Stolz is NOT an author -- NVS contact person for GNF manuscript approval. This manuscript shall NOT be copied to the OAK internet.
Keywords:	tyrosine biosynthesis, prephenate, chorismate, Haemophilus influenzae, structural genomics
Date Deposited:	13 Oct 2015 13:16
Last Modified:	13 Oct 2015 13:16
URI:	https://oak.novartis.com/id/eprint/3110