Structure, Function and Dynamics of a Regulatory Enzyme — Aspartate Transcarbamylase

Schachman, H. K.

doi:10.1007/978-3-642-65456-5_3

Cited by 13 publications

(4 citation statements)

References 27 publications

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“…Instead, one of the two proteins might regulate the activity of the other. The presencelabsence of one would affect the activity of the other, similar to the way in which the regulatory subunit of aspartate transcarbamoylase inhibits the activity of the catalytic subunit (Schachman, 1974). It appears plausible that CheC might regulate CheD in some way, because the phenotypes are exactly opposite: cheD mutants are very tumbly and are not 'excitable' by attractant; cheC mutants are quite smooth swimming and do not adapt to addition of attractant (Rosario, eta/., 1995).…”

Section: Discussionmentioning

confidence: 99%

CheC and CheD interact to regulate methylation of Bacillus subtilis methyl‐accepting chemotaxis proteins

Rosario

Ordal

1996

Molecular Microbiology

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In this study, we have demonstrated that two unique proteins in Bacillus subtilis chemotaxis, CheC and CheD, interact. We have shown this interaction both by using the yeast two-hybrid system and by precipitation of in vitro translated products using glutathione-S-transferase fusions and glutathione agarose beads. We have also shown that CheC inhibits B. subtilis CheR-mediated methylation of B. subtilis methyl-accepting chemotaxis proteins (MCPs) but not of Escherichia coli MCPs. It was previously reported that cheC mutants tend to swim smoothly and do not adapt to addition of attractant; cheD mutants have very poorly methylated MCPs and are very tumbly, similar to cheA mutants. We hypothesize that CheC exerts its effect on MCP methylation in B. subtilis by controlling the binding of CheD to the MCPs. In absence of CheD, the MCPs are poor substrates for CheR and appear to tie up, rather than activate, CheA. The regulation of CheD by CheC may be part of a unique adaptation system for chemotaxis in B. subtilis, whereby high levels of CheY-P brought about by attractant addition would allow CheC to interact with CheD and consequently leave the MCPs, reducing CheA activity and hence the levels of CheY-P.

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Section: Discussionmentioning

confidence: 99%

CheC and CheD interact to regulate methylation of Bacillus subtilis methyl‐accepting chemotaxis proteins

Rosario

Ordal

1996

Molecular Microbiology

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“…The apparent ability of compensating mutations to occur in any phage-host pair of these components would seem puzzling. However, a possibly analogous observation has been made with the multimeric regulatory enzyme aspartate transcarbamylase: mutational changes in the regulatory subunit affect the specificity of the catalytic subunit active site, solely by interaction between the heterologous subunits (26). The recent identification of a host protein defined by a groE mutation (10, 11) should lead to more direct tests for the existence of a functional phage-host protein complex in head assembly.…”

Section: Discussionmentioning

confidence: 85%

Role of the host cell in bacteriophage T4 development. I. Characterization of host mutants that block T4 head assembly

Revel¹,

Stitt²,

Lielausis³

et al. 1980

J Virol

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To study the role of the host cell in bacteriophage T4 infection, we selected more than 600 mutant host-defective bacteria that absorbed and were killed by phage T4+ but were unable to support its growth. The mutants were grouped into seven classes by the growth patterns of T4 phages carrying compensating mutations (go mutants [grows on]), selected on four prototype host-defective strains. Lysis and DNA synthesis experiments indicated that classes A, AD, D, and B (the majority of the host-defective mutants) block T4+ development at an assembly step, class C mutants affect an early stage in phage development, and class F mutants appear to act at more than one stage. Analysis of T4+ infection in the assembly-defective mutants by in vitro complementation, electron microscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the host-defective mutations interfere with T4+ capsid formation at the level of phage gene 31 function, before assembly of any recognizable capsid structure. The mutations map near purA, but at two or possibly three different sites. The go mutant phages able to overcome the host defect carry mutations in either gene 31, as found by others for similar defective hosts, or in the gene for the major capsid protein (gene 23). The gene 23 go mutations do not bypass the requirement for gene 31 function. These results suggest that at least three components must interact to initiate T4 head assembly: gp31, gp23, and one or more host factors. The compensatory effects of mutational alterations in these components are highly allele specific, consistent with the view that phage and host components interact directly in protein complexes.

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“…Properties of its regulatory and catalytic subunits were investigated in detail by enzymology and physical chemistry. 19 The complete structure determined by X-ray diffraction shows that there are six catalytic and six regulatory subunits. 20 In agreement with these findings, Jean-Pierre Changeux in Jacques Monod's laboratory investigated the mechanism of the feedback inhibition of L-threonine deaminase discovered by Edward Adelberg and Umbarger , and from kinetic studies with extracts proposed that this enzyme has inhibitory sites in addition to catalytic ones.…”

Section: Major Mechanisms Of Regulationmentioning

confidence: 99%

Regulatory Molecular Biology

Pardee

2006

Cell Cycle

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Close regulations of molecular biological processes are essential for life. Defective controls cause diseases such as cancer and neurological malfunctions. We now are provided with a plethora of regulatory mechanisms exerted at many levels. Prominent are covalent protein modifications, non-covalent feedback inhibition that modifies enzyme activity, and enzyme induction. Non-covalent or covalent binding to them of either small molecules or proteins act on functional DNA, RNA, proteins and metabolites regulates their production and degradation rates, activities and intra-cell locations. Time frames differ greatly, from seconds to days or longer. A control at every level is balanced by an opposing mechanism: populations of organisms are balanced by birth vs. death, cell synthesis by apoptosis, mutation by DNA repair, macromolecular syntheses by their degradations, metabolite anabolism vs. catabolism, enzyme activation by inhibition, protein kinases by phosphatases. Any abnormal molecular condition is sensed when regulation is defective as in cancer, which leads to its rectification, to cell death, or to disease if this is not possible.

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Structure, Function and Dynamics of a Regulatory Enzyme — Aspartate Transcarbamylase

Cited by 13 publications

References 27 publications

CheC and CheD interact to regulate methylation of Bacillus subtilis methyl‐accepting chemotaxis proteins

CheC and CheD interact to regulate methylation of Bacillus subtilis methyl‐accepting chemotaxis proteins

Role of the host cell in bacteriophage T4 development. I. Characterization of host mutants that block T4 head assembly

Regulatory Molecular Biology

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