Stabilization of radical intermediates by an active-site tyrosine residue in methylmalonyl-CoA mutase

Biochemistry
N H ThomäP F Leadlay

Abstract

The adenosylcobalamin-dependent methylmalonyl-CoA mutase catalyzes the reversible rearrangement of methylmalonyl-CoA into succinyl-CoA by a free-radical mechanism. The recently solved X-ray crystal structure of methylmalonyl-CoA mutase from Propionibacterium shermanii has shown that tyrosine 89 is an active-site residue involved in substrate binding. The role of tyrosine 89, a conserved residue among methylmalonyl-CoA mutases, has been investigated by using site-directed mutagenesis to replace this residue with phenylalanine. The crystal structure of the Tyr89Phe mutant was determined to 2.2 A resolution and was found to be essentially superimposable on that of wild-type. Mutant and wild-type enzyme have very similar KM values, but kcat for the Tyr89Phe mutant is 580-fold lower than for wild-type. The rate of release of tritium from 5'-[3H]adenosylcobalamin during the enzymatic reaction and its rate of appearance in substrate and product were measured. The tritium released was found to partition unequally between methylmalonyl-CoA and succinyl-CoA, in a ratio of 40:60 when the reaction was initiated by addition of methylmalonyl-CoA and in a ratio of 10:90 when the reaction was initiated by addition of succinyl-CoA. The overall ...Continue Reading

References

Oct 5, 2001·Journal of Inorganic Biochemistry·Agnieszka Dybala-Defratyka, Piotr Paneth
Jul 29, 2006·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·R BanerjeePiotr Paneth
Apr 12, 2002·Chembiochem : a European Journal of Chemical Biology·S D WetmoreL Radom
May 25, 2010·Applied Microbiology and Biotechnology·Sun Mee HongTakahiro Kusakabe

Related Concepts

Cobamides
3',4'-anhydroadenosylcobalamin
Methylmalonyl-CoA Mutase
Mutagenesis, Site-Directed
Plain X-ray
Free Radicals
Propionibacterium
Radicals (chemistry)
Crystallography, X-Ray
Intramolecular Transferase Activity

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Sexual Dimorphism in Neurodegeneration

There exist sex differences in neurodevelopmental and neurodegenerative disorders. For instance, multiple sclerosis is more common in women, whereas Parkinson’s disease is more common in men. Here is the latest research on sexual dimorphism in neurodegeneration

HLA Genetic Variation

HLA genetic variation has been found to confer risk for a wide variety of diseases. Identifying these associations and understanding their molecular mechanisms is ongoing and holds promise for the development of therapeutics. Find the latest research on HLA genetic variation here.

Super-resolution Microscopy

Super-resolution microscopy is the term commonly given to fluorescence microscopy techniques with resolutions that are not limited by the diffraction of light. Here are the latest discoveries pertaining to super-resolution microscopy.

Genetic Screens in iPSC-derived Brain Cells

Genetic screening is a critical tool that can be employed to define and understand gene function and interaction. This feed focuses on genetic screens conducted using induced pluripotent stem cell (iPSC)-derived brain cells.

Brain Lower Grade Glioma

Low grade gliomas in the brain form from oligodendrocytes and astrocytes and are the slowest-growing glioma in adults. Discover the latest research on these brain tumors here.

CD4/CD8 Signaling

Cluster of differentiation 4 and 8 (CD8 and CD8) are glycoproteins founds on the surface of immune cells. Here is the latest research on their role in cell signaling pathways.

Alignment-free Sequence Analysis Tools

Alignment-free sequence analyses have been applied to problems ranging from whole-genome phylogeny to the classification of protein families, identification of horizontally transferred genes, and detection of recombined sequences. Here is the latest research.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.