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Papers by Timothy Lilburn

Applied and Environmental Microbiology

arfI encoded the 57.7-kDa subunit of Cytophaga xylanolytica arabinofuranosidase I (ArfI). arfIIen... more arfI encoded the 57.7-kDa subunit of Cytophaga xylanolytica arabinofuranosidase I (ArfI). arfIIencoded a 59.2-kDa subunit of ArfII. Products of both cloned genes liberated arabinose from arabinan and arabinoxylan. The deduced amino acid sequences of ArfI and ArfII revealed numerous regions that were identical to each other and to regions of homologous proteins fromBacteroides ovatus, Bacillus subtilis, andClostridium stercorarium.

arfI encoded the 57.7-kDa subunit of Cytophaga xylanolytica arabinofuranosidase I (ArfI). arfII e... more arfI encoded the 57.7-kDa subunit of Cytophaga xylanolytica arabinofuranosidase I (ArfI). arfII encoded a 59.2-kDa subunit of ArfII. Products of both cloned genes liberated arabinose from arabinan and arabinoxylan. The deduced amino acid sequences of ArfI and ArfII revealed numerous regions that were identical to each other and to regions of homologous proteins from Bacteroides ovatus, Bacillus subtilis, and Clostridium stercorarium.

Biochemistry Usa, 1998

Using mutant strains of Rhodobacter capsulatus and Rhodobacter sphaeroides in which the pufX gene... more Using mutant strains of Rhodobacter capsulatus and Rhodobacter sphaeroides in which the pufX gene had been deleted, it was possible to identify by HPLC membrane protein components present in pufX + cells but absent in pufXcells. In parallel preparations, membrane proteins soluble in chloroform/ methanol containing ammonium acetate were first extracted from lyophilized membrane fractions of the pufX + cells and separated from pigments and larger protein material by gel-filtration chromatography. Protein-containing fractions were examined by HPLC, and several peaks were collected from pufX + material that were not present in pufXmaterial. From N-terminal amino acid sequencing, the PufX protein of Rb. capsulatus was identified, and from positive interaction with a PufX protein antibody, the Rb. sphaeroides PufX protein was identified. Although overall yields were very small, sufficient quantities of these proteins were isolated to evaluate their effect on the reconstitution of the core light-havesting antenna (LH1) and its subunit complex. From the behavior of the PufX protein and the R-polypeptide of LH1 on HPLC, qualitative evidence was obtained that the two proteins have a high affinity for each other. In reconstitution assays with bacteriochlorophyll (Bchl) and the LH1 Rand-polypeptides of Rb. capsulatus, the PufX protein of Rb. capsulatus was inhibitory to LH1 formation at low concentration. A similar inhibition was exhibited by Rb. sphaeroides PufX protein for reconstitution of LH1 with Bchl and the LH1 Rand-polypeptides of Rb. sphaeroides. In both cases, the ratios of concentrations of the PufX protein to the R-polypeptide causing 50% inhibition were approximately 0.5. Formation of the heterologous (R) subunit-type complex formed with Bchl and the Rand-polypeptides of LH1 of Rb. capsulatus was also inhibited by low concentrations of the Rb. capsulatus PufX protein (approximately 50% inhibition at PufX:R-polypeptide ratios) 0.5). However, neither PufX protein inhibited formation of a homologous () subunit-type complex, which indicates that the PufX proteins do not interact with the-polypeptides.