scholarly journals Importance of the carboxyl-terminal domain of enzyme I of the Escherichia coli phosphoenolpyruvate: sugar phosphotransferase system for phosphoryl donor specificity.

1996 ◽  
Vol 93 (1) ◽  
pp. 347-351 ◽  
Author(s):  
Y. J. Seok ◽  
B. R. Lee ◽  
P. P. Zhu ◽  
A. Peterkofsky
Keyword(s):  
Escherichia Coli ◽  
Phosphotransferase System ◽  
Terminal Domain ◽  
Carboxyl Terminal Domain ◽  
Carboxyl Terminal ◽  
Enzyme I

scholarly journals Inhibition of F1-ATPase Rotational Catalysis by the Carboxyl-terminal Domain of the ϵ Subunit

2014 ◽  
Vol 289 (44) ◽  
pp. 30822-30831 ◽  
Author(s):  
Mayumi Nakanishi-Matsui ◽  
Mizuki Sekiya ◽  
Shio Yano ◽  
Masamitsu Futai
Keyword(s):  
Escherichia Coli ◽  
Atpase Activity ◽  
Atp Synthase ◽  
Single Molecule ◽  
Inhibitory Effect ◽  
Rotational Catalysis ◽  
Terminal Domain ◽  
Carboxyl Terminal Domain ◽  
Carboxyl Terminal ◽  
Loop 2

Escherichia coli ATP synthase (F0F1) couples catalysis and proton transport through subunit rotation. The ϵ subunit, an endogenous inhibitor, lowers F1-ATPase activity by decreasing the rotation speed and extending the duration of the inhibited state (Sekiya, M., Hosokawa, H., Nakanishi-Matsui, M., Al-Shawi, M. K., Nakamoto, R. K., and Futai, M. (2010) Single molecule behavior of inhibited and active states of Escherichia coli ATP synthase F1 rotation. J. Biol. Chem. 285, 42058–42067). In this study, we constructed a series of ϵ subunits truncated successively from the carboxyl-terminal domain (helix 1/loop 2/helix 2) and examined their effects on rotational catalysis (ATPase activity, average rotation rate, and duration of inhibited state). As expected, the ϵ subunit lacking helix 2 caused about ½-fold reduced inhibition, and that without loop 2/helix 2 or helix 1/loop 2/helix 2 showed a further reduced effect. Substitution of ϵSer108 in loop 2 and ϵTyr114 in helix 2, which possibly interact with the β and γ subunits, respectively, decreased the inhibitory effect. These results suggest that the carboxyl-terminal domain of the ϵ subunit plays a pivotal role in the inhibition of F1 rotation through interaction with other subunits.

scholarly journals Mutational Inactivation of a Gene Homologous to Escherichia coli ptsP Affects Poly-β-Hydroxybutyrate Accumulation and Nitrogen Fixation in Azotobacter vinelandii

1998 ◽  
Vol 180 (18) ◽  
pp. 4790-4798 ◽  
Author(s):  
Daniel Segura ◽  
Guadalupe Espín
Keyword(s):  
Escherichia Coli ◽  
Azotobacter Vinelandii ◽  
Growth Defect ◽  
Nucleotide Sequencing ◽  
Acetylene Reduction Activity ◽  
Respiratory Protection ◽  
Phosphotransferase System ◽  
Terminal Domain ◽  
Diazotrophic Growth ◽  
Enzyme I

ABSTRACT Strain DS988, an Azotobacter vinelandii mutant with a reduced capacity to accumulate poly-β-hydroxybutyrate, was isolated after mini-Tn5 mutagenesis of the UW136 strain. Cloning and nucleotide sequencing of the affected locus revealed a gene homologous to Escherichia coli ptsP which encodes enzyme INtr, a homologue of enzyme I of the phosphoenol pyruvate-sugar phosphotransferase system with an N-terminal domain similar to the N-terminal domain of some NifA proteins. Strain DS988 was unable to grow diazotrophically with 10 mM glucose as a carbon source. Diazotrophic growth on alternative carbon sources such as gluconate was only slightly affected. Glucose uptake, as well as glucose kinase and glucose-6-phosphate-dehydrogenase activities that lead to the synthesis of gluconate-6-phosphate, were not affected by the ptsP mutation. The inability of DS988 to grow diazotrophically in 10 mM glucose was overcome by supplying ammonium or other sources of fixed nitrogen. Acetylene reduction activity but not transcription of the nitrogenase structural gene nifH was shown to be impaired in strain DS988 when it was incubated in 10 mM glucose. The diazotrophic growth defect of DS988 was restored either by increasing the glucose concentration to above 20 mM or by lowering the oxygen concentration. These data suggest that a mutation inptsP leads to a failure in poly-β-hydroxybutyrate metabolism and in the respiratory protection of nitrogenase under carbon-limiting conditions.

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