PMID- 17154531
OWN - NLM
STAT- MEDLINE
DCOM- 20070221
LR  - 20181113
IS  - 0006-2960 (Print)
IS  - 1520-4995 (Electronic)
IS  - 0006-2960 (Linking)
VI  - 45
IP  - 50
DP  - 2006 Dec 19
TI  - Substrate recognition by the hetero-octameric ATP phosphoribosyltransferase from 
      Lactococcus lactis.
PG  - 14933-43
AB  - Two families of ATP phosphoribosyl transferases (ATP-PRT) join ATP and 
      5-phosphoribosyl-1 pyrophosphate (PRPP) in the first reaction of histidine 
      biosynthesis. These consist of a homohexameric form found in all three kingdoms 
      and a hetero-octameric form largely restricted to bacteria. Hetero-octameric 
      ATP-PRTs consist of four HisGS catalytic subunits related to periplasmic binding 
      proteins and four HisZ regulatory subunits that resemble histidyl-tRNA 
      synthetases. To clarify the relationship between the two families of ATP-PRTs and 
      among phosphoribosyltransferases in general, we determined the steady state 
      kinetics for the hetero-octameric form and characterized the active site by 
      mutagenesis. The KmPRPP (18.4 +/- 3.5 microM) and kcat (2.7 +/- 0.3 s-1) values 
      for the PRPP substrate are similar to those of hexameric ATP-PRTs, but the Km for 
      ATP (2.7 +/- 0.3 mM) is 4-fold higher, suggestive of tighter regulation by energy 
      charge. Histidine and AMP were determined to be noncompetitive (Ki = 81.1 microM) 
      and competitive (Ki = 1.44 mM) inhibitors, respectively, with values that 
      approximate their intracellular concentrations. Mutagenesis experiments aimed at 
      investigating the side chains recognizing PRPP showed that 5'-phosphate contacts 
      (T159A and T162A) had the largest (25- and 155-fold, respectively) decreases in 
      kcat/Km, while smaller decreases were seen with mutants making cross subunit 
      contacts (K50A and K8A) to the pyrophosphate moiety or contacts to the 2'-OH 
      group. Despite their markedly different quaternary structures, hexameric and 
      hetero-octameric ATRP-PRTs exhibit similar functional parameters and employ 
      mechanistic strategies reminiscent of the broader PRT superfamily.
FAU - Champagne, Karen S
AU  - Champagne KS
AD  - Department of Microbiology and Molecular Genetics, University of Vermont, B403 
      Given Building, 89 Beaumont Avenue, Burlington, Vermont 05405, USA.
FAU - Piscitelli, Elise
AU  - Piscitelli E
FAU - Francklyn, Christopher S
AU  - Francklyn CS
LA  - eng
GR  - R01 GM054899-09/GM/NIGMS NIH HHS/United States
GR  - GM54899/GM/NIGMS NIH HHS/United States
GR  - R01 GM054899/GM/NIGMS NIH HHS/United States
GR  - R01 GM054899-06S1/GM/NIGMS NIH HHS/United States
GR  - R01 GM054899-10/GM/NIGMS NIH HHS/United States
GR  - R01 GM054899-11/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Bacterial Proteins)
RN  - 0 (Multiprotein Complexes)
RN  - 0 (Protein Subunits)
RN  - 415SHH325A (Adenosine Monophosphate)
RN  - 4QD397987E (Histidine)
RN  - 7540-64-9 (Phosphoribosyl Pyrophosphate)
RN  - EC 2.4.2.17 (ATP Phosphoribosyltransferase)
SB  - IM
MH  - ATP Phosphoribosyltransferase/*chemistry/genetics/metabolism
MH  - Adenosine Monophosphate/chemistry
MH  - Bacterial Proteins/*chemistry/genetics/metabolism
MH  - Binding Sites
MH  - Catalytic Domain/genetics
MH  - Histidine/biosynthesis/chemistry
MH  - Lactococcus lactis/*enzymology/genetics
MH  - Multiprotein Complexes/*chemistry/genetics/metabolism
MH  - Mutagenesis, Site-Directed
MH  - Phosphoribosyl Pyrophosphate/chemistry/metabolism
MH  - Protein Binding/genetics
MH  - Protein Structure, Quaternary/genetics
MH  - Protein Subunits/chemistry/genetics/metabolism
MH  - Substrate Specificity/genetics
PMC - PMC2567060
MID - NIHMS61630
EDAT- 2006/12/13 09:00
MHDA- 2007/02/22 09:00
PMCR- 2008/10/14
CRDT- 2006/12/13 09:00
PHST- 2006/12/13 09:00 [pubmed]
PHST- 2007/02/22 09:00 [medline]
PHST- 2006/12/13 09:00 [entrez]
PHST- 2008/10/14 00:00 [pmc-release]
AID - 10.1021/bi061802v [doi]
PST - ppublish
SO  - Biochemistry. 2006 Dec 19;45(50):14933-43. doi: 10.1021/bi061802v.