Effector Response of the Aspartate Transcarbamoylase From Wild Type Pseudomonas Putida and a Mutant with 11 Amino Acids Deleted at the N-terminus of PyrB.

Like its enteric counterpart, aspartate transcarbamoylase (ATCase) from Pseudomonas putida is a dodecamer of two different polypeptides. Unlike the enterics, the Pseudomonas ATCase lacks regulatory polypeptides but employs instead inactive dihydroorotases for an active dodecamer. Previous work showed that PyrB contains not only the active site but also the effector binding sites for ATP, UTP and CTP at its N-terminus. In this work, 11 amino acids were deleted from the N-terminus of PyrB and the ATCase with the truncated protein was expressed in E. coli pyrB- and purified. The wild type enzyme was similarly treated. Velocity-substrate plots without effectors gave Michaelis-Menten kinetics in all cases. Deleting 11 amino acids did not affect dodecameric assembly but altered effector responses. When carbamoylphosphate was varied, the mutant enzyme was inhibited by UTP while the wild type enzyme was activated 2-fold. When the aspartate was varied, CTP had no effect on the mutant enzyme but strongly inhibited the wild type enzyme.

Grantor dc:publisher

University of North Texas

Year dc:date

2002

Author dc:creator

• Asfour, Hani

Contributors dc:contributor

• O'Donovan, Gerard A.
• Farinha, Mark A.
• Benjamin, Robert C.

• Pyrimidine nucleotides -- Metabolism.
• Pseudomonas.
• UTP
• dodecamer
• ATCase
• ATP
• pyrimidine pathway

Statement dc:rights

• Public
• Copyright
• Asfour, Hani
• Copyright is held by the author, unless otherwise noted. All rights reserved.

Language dc:language

English

Identifier

oclc: 54829013
https://digital.library.unt.edu/ark:/67531/metadc3163/
ark: ark:/67531/metadc3163

OAI identifier oai:identifier

info:ark/67531/metadc3163