William W. Metcalf
Professor of Microbiology
metcalf@life.uiuc.edu
B.S. (Anthropology), University
of Illinois, 1981
B.S. (Microbiology), University of Illinois, 1984
Ph.D. (Microbiology), Purdue University, 1991
Postdoctural (Microbiology), Purdue University, 1991-1993
Postdoctural (Microbiology), University of Illinois, 1993-1997
Molecular genetics and biochemistry of methanogenic Archaea; redox cycling of phosphorus by microorganisms
Genetic analysis of methanogenic Archaea
Methanogenesis is critically important to a number of human-related problems
including the production of alternative fuels from biological materials,
waste treatment, and global warming (via production of a key greenhouse
gas). Each year an estimated 5 x 1014 g of biologically produced methane
is released into the atmosphere. Depending on your viewpoint, this represents
a staggering untapped renewable energy source and/or a frightening contribution
to global warming. Methanogenesis also plays an essential role in the
global carbon cycle, is relevant to agriculture due to its role in ruminant
nutrition and is a required step in the processing of waste in sewage
treatment facilities and landfills. In addition, methanogens comprise
one of the few experimentally tractable groups among the Archaea and,
thus, provide outstanding model organisms for the study of this so-called
"third form of life".
A major focus of research in my laboratory has been the development of
genetic methods for use in the methanogenic archaeon Methanosarcina. Over
the past five years, we have developed a collection of genetic tools and
methods for use in Methanosarcina that are unsurpassed among methanoarchaea.
These tools include; plasmid shuttle vectors, very high efficiency transformation,
in vivo transposon mutagenesis, multiple selectable markers and an anaerobic
incubator for large-scale growth on solid media. More recently, we have
applied these methods to study the metabolism and physiology of Methanosarcina
species. We showed that directed mutagenesis of specific genes is possible
in two Methanosarcina species and have constructed dozens of mutant strains
with lesions in over 15 different genes. Significantly, many of these
strains have mutations in genes required for methanogenesis. The study
of these mutants has revealed novel aspects of the methanogenic process.
We have also adapted reporter gene fusions for use in Methanosarcina and
shown that genes required for specific methanogenic pathways are transcriptionally
regulated by availability of their substrate.
Microbial metabolism of reduced phosphorus compounds
The second project underway in my laboratory involves characterizing of
the microbial metabolism of reduced phosphorus compounds. Phosphorus plays
a central role in the metabolism of all living organisms and is a required
nutrient. Despite the ubiquitous role of P in biology, the biochemistry
of P containing compounds is generally considered to be quite simple,
consisting almost entirely of phosphate-ester formation and hydrolysis.
However, it is increasingly apparent that other types of P biochemistry
are important as well. Some of these reactions involve compounds in which
P is at a lower valence state, suggesting that previously unsuspected
P redox reactions may be important in the metabolism of this element.
We have focused our studies on the metabolism
of two reduced P compounds, phosphite and hypophosphite using of a combined
approach that includes genetic, molecular and biochemical techniques.
Surprisingly, organisms with metabolic pathways that allow oxidation of
these compounds are quite common, with ca. 1% of all microorganisms being
able to oxidize phosphite. We have isolated numerous microorganisms that
are capable of oxidizing both hypophosphite and phosphite. Examination
of these bacteria revealed at least three previously unknown pathways
for oxidation of reduced P compounds, each of which is currently under
study in my laboratory. Two novel phosphorus-oxidizing enzymes have been
discovered and characterized during the course of this work. Interestingly,
one of these has great potential as a cofactor-regenerating enzyme for
use in biocatalysis. Preliminary data suggests that additional novel pathways
are present among our isolates. In addition to these studies on phosphorus
oxidation, we have recently begun genetic studies on phosphonate biosynthesis
in Streptomyces. We hope that these studies will expand our concept of
P metabolism and shed new light on the biochemical and physiological properties
of reduced P compounds.
Vrtis, J.M., Metcalf, W.W., and van der Donk, W.A. (2002) "Phosphite Dehydrogenase, a New Versatile Cofactor Regeneration Enzyme," Angew. Chem. Int. Ed. 41: 3257-3259. [Abstract]
White, A.K. and Metcalf, W.W. (2002) "Purification and biochemical characterization of HtxA, a novel phosphorus oxidizing enzyme with hypophosphite:2-oxoglutarate dioxygenase activity," J. Biol. Chem. 277: 38262-38271. [Abstract]
Galagan, J.E., Nusbaum, C., Roy, A., Endrizzi, M.G., Macdonald, P., FitzHugh, W., Calvo, S., Engels, R., Smirnov, S., Atnoor, D., Brown, A., Allen, N., Naylor, J., Stange-Thomann, N., DeArellano, K., Johnson, R., Linton, L., McEwan, P., McKernan, K., Talamas, J., Tirrell, A., Ye, W., Zimmer, A., Barber, R.D., Cann, I., Graham, D.E., Grahame, D.A., Guss, A.M., Hedderich, R., Ingram-Smith, C., Kuettner, H.C., Krzycki, J.A., Leigh, J.A., Li, W., Liu, J., Mukhopadhyay, B., Reeve, J.N., Smith, K., Springer, T.A., Umayam, L.A., White, O., White, R.H., Conway de Macario, E., Ferry, J.G., Jarrell, K.F., Jing, H., Macario, A.J., Paulsen, I., Pritchett, M., Sowers, K.R., Swanson, R.V., Zinder, S.H., Lander E., Metcalf W.W. and Birren, B. (2002) "The genome of Methanosarcina acetivorans reveals extensive metabolic and physiological diversity," Genome Res. 12: 532-542. [Abstract]
Meuer, J., Kuettner, H.C., Zhang, J.K., Hedderich, R., and Metcalf, W.W. (2002) "Genetic analysis of the archaeon Methanosarcina barkeri Fusaro reveals a central role for Ech hydrogenase and ferredoxin in methanogenesis and carbon fixation," Proc. Natl. Acad. Sci. 99: 5632-5637. [Abstract]
Zhang, J.K., White, A.K., Kuettner, H.C., Boccazzi, P., and Metcalf, W.W. (2002) "Directed mutagenesis and plasmid-based complementation in the methanogenic archaeon Methanosarcina acetivorans C2A demonstrated by genetic analysis of proline biosynthesis," J. Bacteriol. 184: 1449-1454. [Abstract]
Costas, A.M., White, A.K., and Metcalf, W.W. (2001) "Purification and characterization of a novel phosphorus-oxidizing enzyme from Pseudomonas stutzeri WM88," J. Biol. Chem. 276: 17429-36. [Abstract]
View Publications by William W. Metcalf listed on the National Library of Medicine (PubMed)