Brian Steer
Verenium Corporation
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Featured researches published by Brian Steer.
Applied and Environmental Microbiology | 2004
Yali Brennan; Walter Callen; Leif Christoffersen; Paul Dupree; Florence Goubet; Shaun Healey; Myrian Hernández; Martin S. Keller; Ke Li; Nisha Palackal; Ana Sittenfeld; Giselle Tamayo; Steve Wells; Geoffrey P. Hazlewood; Eric J. Mathur; Jay M. Short; Dan E. Robertson; Brian Steer
ABSTRACT Recombinant DNA technologies enable the direct isolation and expression of novel genes from biotopes containing complex consortia of uncultured microorganisms. In this study, genomic libraries were constructed from microbial DNA isolated from insect intestinal tracts from the orders Isoptera (termites) and Lepidoptera (moths). Using a targeted functional assay, these environmental DNA libraries were screened for genes that encode proteins with xylanase activity. Several novel xylanase enzymes with unusual primary sequences and novel domains of unknown function were discovered. Phylogenetic analysis demonstrated remarkable distance between the sequences of these enzymes and other known xylanases. Biochemical analysis confirmed that these enzymes are true xylanases, which catalyze the hydrolysis of a variety of substituted β-1,4-linked xylose oligomeric and polymeric substrates and produce unique hydrolysis products. From detailed polyacrylamide carbohydrate electrophoresis analysis of substrate cleavage patterns, the xylan polymer binding sites of these enzymes are proposed.
Protein Science | 2004
Nisha Palackal; Yali Brennan; Walter Callen; Paul Dupree; Gerhard Frey; Florence Goubet; Geoffrey P. Hazlewood; Shaun Healey; Young E. Kang; Keith Kretz; Edd Lee; Xuqiu Tan; Geoffery L. Tomlinson; John Verruto; Vicky W.K. Wong; Eric J. Mathur; Jay M. Short; Dan E. Robertson; Brian Steer
Directed evolution technologies were used to selectively improve the stability of an enzyme without compromising its catalytic activity. In particular, this article describes the tandem use of two evolution strategies to evolve a xylanase, rendering it tolerant to temperatures in excess of 90°C. A library of all possible 19 amino acid substitutions at each residue position was generated and screened for activity after a temperature challenge. Nine single amino acid residue changes were identified that enhanced thermostability. All 512 possible combinatorial variants of the nine mutations were then generated and screened for improved thermal tolerance under stringent conditions. The screen yielded eleven variants with substantially improved thermal tolerance. Denaturation temperature transition midpoints were increased from 61°C to as high as 96°C. The use of two evolution strategies in combination enabled the rapid discovery of the enzyme variant with the highest degree of fitness (greater thermal tolerance and activity relative to the wild‐type parent).
Applied Microbiology and Biotechnology | 2007
Nisha Palackal; Christopher Scott Lyon; Seema Zaidi; Peter Luginbühl; Paul Dupree; Florence Goubet; John L. Macomber; Jay M. Short; Geoffrey P. Hazlewood; Dan E. Robertson; Brian Steer
A unique multifunctional glycosyl hydrolase was discovered by screening an environmental DNA library prepared from a microbial consortium collected from cow rumen. The protein consists of two adjacent catalytic domains. Sequence analysis predicted that one domain conforms to glycosyl hydrolase family 5 and the other to family 26. The enzyme is active on several different β-linked substrates and possesses mannanase, xylanase, and glucanase activities. Site-directed mutagenesis studies on the catalytic residues confirmed the presence of two functionally independent catalytic domains. Using site-specific mutations, it was shown that one catalytic site hydrolyzes β-1,4-linked mannan substrates, while the second catalytic site hydrolyzes β-1,4-linked xylan and β-1,4-linked glucan substrates. Polysaccharide Analysis using Carbohydrate gel Electrophoresis (PACE) also confirmed that the enzyme has discrete domains for binding and hydrolysis of glucan- and mannan-linked polysaccharides. Such multifunctional enzymes have many potential industrial applications in plant processing, including biomass saccharification, animal feed nutritional enhancement, textile, and pulp and paper processing.
Current Opinion in Chemical Biology | 2004
Dan E. Robertson; Brian Steer
Archive | 2004
Brian Steer; Walter Callen; Shaun Healey; Derrick Pulliam
Archive | 2003
Brian Steer; Walter Callen; Shaun Healey; Geoff Hazlewood; Di Wu; David Blum; Alireza Esteghlalian
Archive | 2003
Brian Steer; Walter Callen; Shaun Healey; Geoff Hazlewood; Di Wu; David Blum; Alireza Esteghlalian
Archive | 2013
Arne Solbak; Brian Steer; Mark Dycaico; Katie Kline; Axel Trefzer; Thomas Todaro; Fatima El-Farrah; Alberto Alvarado; Gerhard Frey
Archive | 2007
Brian Steer; Shaun Healey; Alireza Esteghlalian; Stacy Marie Miles; Kenneth Barrett; Rene Quadt
Archive | 2010
Walter Callen; Shaun Healey; Derrick Pulliam; Brian Steer; ウォルター カレン; ブライアン スティア; ショーン ヒーリー; デリク プリアム