Jan Kok
Autonomous University of Barcelona
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Publication
Featured researches published by Jan Kok.
Journal of Biological Chemistry | 2000
Eduard Torrents; Girbe Buist; Aimin Liu; Rolf Eliasson; Jan Kok; Isidre Gibert; Astrid Gräslund; P Reichard
Lactococcus lactis contains an operon with the genes (nrdD and nrdG) for a class III ribonucleotide reductase. Strict anaerobic growth depends on the activity of these genes. Both were sequenced, cloned, and overproduced in Escherichia coli. The corresponding proteins, NrdD and NrdG, were purified close to homogeneity. The amino acid sequences of NrdD (747 residues, 84.1 kDa) and NrdG (199 residues, 23.3 kDa) are 53 and 42% identical with the respective E. coli proteins. Together, they catalyze the reduction of ribonucleoside triphosphates to the corresponding deoxyribonucleotides in the presence ofS-adenosylmethionine, reduced flavodoxin or reduced deazaflavin, potassium ions, dithiothreitol, and formate. EPR experiments demonstrated a [4Fe-4S]+ cluster in reduced NrdG and a glycyl radical in activated NrdD, similar to the E. coli NrdD and NrdG proteins. Different from E. coli, the two polypeptides of NrdD and the proteins in the NrdD-NrdG complex were only loosely associated. Also the FeS cluster was easily lost from NrdG. The substrate specificity and overall activity of the L. lactis enzyme was regulated according to the general rules for ribonucleotide reductases. Allosteric effectors bound to two separate sites on NrdD, one binding dATP, dGTP, and dTTP and the other binding dATP and ATP. The two sites showed an unusually high degree of cooperativity with complex interactions between effectors and a fine-tuning of their physiological effects. The results with theL. lactis class III reductase further support the concept of a common origin for all present day ribonucleotide reductases.
Archive | 1998
Girbe Buist; Cornelis Johannes Leenhouts; Gerard Venema; Jan Kok
Archive | 2002
Cornelis Johannes Leenhouts; Ranjan Ramasamy; Anton Steen; Jan Kok; Girbe Buist; Oscar Paul Kuipers
Archive | 2005
Cornelis Johannes Leenhouts; Ranjan Ramasamy; Anton Steen; Jan Kok; Girbe Buist; Oscar Paul Kuipers
Archive | 2013
Wout Overkamp; Katrin Beilharz; Ruud Detert; Oude Weme; Ana Solopova; Harma Karsens; Ákos T. Kovács; Jan Kok; Oscar P. Kuipers; Jan-Willem
Archive | 2012
Ana Rute Neves; Oscar P. Kuipers; Ana Solopova; Herwig Bachmann; Bas Teusink; Jan Kok
Archive | 2007
Arjen Nauta; Oscar P. Kuipers; Jan Kok; Jan Sikkema; Christiaan Daniël c Den Hengst
Archive | 2006
Girbe Buist; Anja N. J. A. Ridder; Jan Kok; Oscar Paul Kuipers
Archive | 2006
Ana Rute Neves; Wietske A. Pool; Rute Castro; Ana Mingote; Filipe Branco dos Santos; Jan Kok; Oscar P. Kuipers; Helena Santos
Archive | 2004
Hengst Christiaan Daniel Den; Olivera Gajic; Oscar P. Kuipers; Jan Kok; Jan Sikkema; Johannes Marie Wilhelmus Geurts; Arjen Nauta