[124] Gillen CD, Andrews HA, Prior P, Allan RN. Crohn's disease and colorectal cancer. Gut

1994;35:651-655.

[125] Savoca PE, Ballantyne GH, Cahow CE. Gastrointestinal malignancies in Crohn’s

disease: a 20-year experience. Dis Colon Rectum 1990;33:7-11.

[126] van Noort BA, Bos PJ, Klopping C, Wilmink JM. Optic neuropathy from thiamine

deficiency in a patient with ulcerative colitis. Doc Ophthalmol 1987;67:45-51.

[127] Zaki I, Millard L. Pellagra complicating Crohn's disease. Postgrad Med J 1995;71:496-

497.

[128] Pollack S, Enat R, Haim S, Zinder O, Barzilai D. Pellagra as the presenting

manifestation of Crohn's disease. Gastroenterology 1982;82:948-952.

[129] Dufier JL, Chaine G, Brasnu C, Duhamel JL, Ricour C, Saurat JH, Royer P,Polliot L. A

case of palpebral ariboflavinosis. Bull Soc Ophtalmol Fr 1980;80:1173-1174. French.

[130] Duhamel JF, Ricour C, Dufier JL, Saurat JH, Drillon P, Navarro J, Royer P. Vitamin

B2 deficiency and total parenteral nutrition. Arch Fr Pediatr 1979;36:342-346.

[131] Cattaneo M, Vecchi M, Zighetti ML, Saibeni S, Martinelli I, Omodei P, Mannucci PM,

de Franchis R. High prevalence of hyperchomocysteinemia in patients with

inflammatory bowel disease: a pathogenic link with thromboembolic complications?

Thromb Haemost 1998;80:542-545.

[132] Vermeulen EG, Stehouwer CD, Valk J, van der Knaap M, van den Berg M, Twisk JW,

Prevoo W, Rauwerda JA. Effect of homocysteine-lowering treatment with folic acid

plus vitamin B on cerebrovascular atherosclerosis and white matter abnormalities as

80 Petros Zezos and Georgios Kouklakis

determined by MRA and MRI: a placebo-controlled, randomized trial. Eur J Clin

Invest 2004;34:256-261.

[133] Vermeulen EG, Stehouwer CD, Twisk JW, van den Berg M, de Jong SC, Mackaay AJ,

van Campen CM, Visser FC, Jakobs CA, Bulterjis EJ, Rauwerda JA. Effect of

homocysteine-lowering treatment with folic acid plus vitamin B6 on progression of

subclinical atherosclerosis: a randomised, placebo-controlled trial. Lancet

2000;355:517-522.

[134] Toole JF, Malinow MR, Chambless LE, Spence JD, Pettigrew LC, Howard VJ, Sides

EG, Wang CH, Stampfer M. Lowering homocysteine in patients with ischemic stroke

to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention

for Stroke Prevention (VISP) randomized controlled trial. JAMA 2004;291:565-575.

[135] den Heijer M, Willems HP, Blom HJ, Gerrits WB, Cattaneo M, Eichinger S, Rosendaal

FR, Bos GM. Homocysteine lowering by B vitamins and the secondary prevention of

deep vein thrombosis and pulmonary embolism: A randomized, placebo-controlled,

double-blind trial. Blood 2007;109:139-144.

[136] Cravo ML, Albuquerque CM, Salazar de Sousa L, Gloria LM, Chaves P, Dias Pereira

A, Nobre Leitao C, Quina MG, Costa Mira F. Microsatellite instability in nonneoplastic mucosa of patients with ulcerative colitis: effect of folate supplementation.

Am J Gastroenterol 1998;93:2060-2064.

[137] Biasco G, Zannoni U, Paganelli GM, Santucci R, Gionchetti P, Rivolta G, Miniero R,

Pironi L, Calabrese C, Di Febo G, Miglioli M. Folic acid supplementation and cell

kinetics of rectal mucosa in patients with ulcerative colitis. Cancer Epidemiol

Biomarkers Prev 1997;6:469-471.

[138] Kim YI. Folate: a magic bullet or a double edged sword for colorectal cancer

prevention? Gut 55:1387-1389.

In: Vitamin B: New Research ISBN 978-1-60021-782-1

Editor: Charlyn M. Elliot, pp. 81-98 © 2008 Nova Science Publishers, Inc.

Chapter V

NEW BACTERIAL COBALAMIN-DEPENDENT

COA-CARBONYL MUTASES INVOLVED IN

DEGRADATION PATHWAYS

Thore Rohwerder1,∗ and Roland H. Müller2

1

Aquatic Biotechnology, Biofilm Centre, University Duisburg-Essen, Geibelstr. 41, D47057 Duisburg, Germany;

2

Department of Environmental Microbiology, Helmholtz Centre for Environmental

Research UFZ, Permoserstr. 15, D-04318 Leipzig, Germany.

ABSTRACT

The adenosylcobalamin-dependent CoA-carbonyl mutases catalyze the 1,2-

rearrangement of carbonyl groups reversibly converting branched-chain carbonic acids

into straight-chain ones. Currently, this enzyme group comprises of only two known

mutases, the extensively studied methylmalonyl-CoA mutase (MCM, EC 5.4.99.2) and

isobutyryl-CoA mutase (ICM, EC 5.4.99.13). Whereas MCM is widespread among

bacteria and animals ICM seems to be restricted to bacteria and has thus far only been

characterized in Streptomyces spp. Both enzymes have a rather limited substrate

spectrum and function effectively merely with their natural substrates methylmalonylCoA and isobutyryl-CoA, respectively. Interestingly, we have recently discovered a

novel bacterial CoA-carbonyl mutase catalyzing the conversion of 2-hydroxyisobutyrylCoA into 3-hydroxybutyryl-CoA (Rohwerder et al. 2006, Appl. Environ. Microbiol.

72:4128). This enzyme plays a central role in the productive degradation of compounds

containing a tert-butyl group such as the common fuel additives methyl and ethyl tertbutyl ether. Similar enzymes are proposed to be involved in the conversion of pivalic

acid and in the degradation of alkanes and alkylated aromatic hydrocarbons via anaerobic

pathways employing addition to fumarate. Since all these compounds are important

∗

 Correspondence concerning this article should be addressed to: Thore Rohwerder, Aquatic Biotechnology,

Biofilm Centre, University Duisburg-Essen, Geibelstr. 41, D-47057 Duisburg, Germany, e-mail:

thore.rohwerder@uni-due.de.

82 Thore Rohwerder and Roland H. Müller

pollutants of water and soil, cobalamin and the new CoA-carbonyl mutases play a thus

far not realized role in natural as well as induced bioremediation processes. Therefore,

we summarize in this chapter the known reactions and also speculate about further

pathways which have not yet been associated with CoA-carbonyl mutase activity. In

addition, the enzyme structure and the herewith possibly associated evolution of substrate

specificity are outlined. Finally, energetic and kinetic consequences are discussed which

may result from employing a cobalamin-dependent enzyme for dissimilatory pathways.

INTRODUCTION

The cobalamin-dependent CoA-carbonyl mutases are a group of enzymes catalyzing the

spectacular 1,2-rearrangement of the CoA thioester moiety of CoA-activated carbonic acids.

In this reaction, the cofactor adenosylcobalamin is used to create radical intermediates.

Currently, only two representatives of this enzyme group are known, the extensively studied

and widespread methylmalonyl-CoA mutase (MCM, EC 5.4.99.2) and isobutyryl-CoA

mutase (ICM, EC 5.4.99.13). MCM catalyzes the reversible and stereospecific conversion of

(R)-methylmalonyl-CoA into succinyl-CoA (eq. 1).

H

-

OOC COSCoA

CH3

H

-

OOC

COSCoA

H2C

H

MCM

(R)-methylmalonyl-CoA succinyl-CoA

(1)

This mutase has been found in a variety of bacteria and also in animals, in which the

enzyme is located in the mitochondria (Gruber & Kratky 2001). The animal MCM is

involved in the conversion of branched-chain amino acids, odd-chain fatty acids and

cholesterol via propionate and methylmalonyl-CoA into succinyl-CoA (Willard & Rosenberg

1980). Any impairment of the mutase results in a serious disorder of organic acid metabolism

termed methylmalonic aciduria (Deodato et al. 2006). In contrast, bacterial propionate

degradation is much more diverse and, consequently, MCM catalysis is not always required

(Textor et al. 1997). However, additional functions of bacterial MCMs are known, including

also the catalysis of the reverse reaction from succinyl-CoA to methylmalonyl-CoA. For

example, in some fermenting bacteria, such as Propionibacterium shermanii, propionate is

not a metabolic intermediate but the end product of the anaerobic degradation of lactate or

pyruvate. Here, MCM is employed for synthesizing propionate from tricarboxylic acid-cycle

(TCC) intermediates via methylmalonyl-CoA (Allen et al. 1964). In Streptomyces spp., MCM

together with ICM is involved in secondary metabolism, providing building blocks for

polyketide antibiotic synthesis (Birch et al. 1993).

In contrast to MCM, ICM seems to be restricted to bacteria and has thus far only been

characterized in the above mentioned Streptomyces spp. (Ratnatilleke et al. 1999; Zerbe-

New Bacterial CoA-Carbonyl Mutases 83

Burkhardt et al. 1998). It catalyzes the reversible conversion of isobutyryl-CoA into butyrylCoA. Although stereospecificity is not as stringent as in MCM, an analogous retention of

configuration is also predominating in ICM (Moore et al. 1995) (eq. 2).

(2)