The oxygen reaction of the cytochrome d-terminated respiratory chain of Escherichia coli at sub-zero temperatures: Kinetic resolution by EPR spectroscopy of two high-spin cytochromes

The oxygen reaction of the fully reduced respiratory chain in membranes from oxygen-limited Escherichia coli was studied at sub-zero temperatures using EPR spectroscopy. Laser photolysis of CO-liganded cytochrome oxidase d precedes oxidation of at least 2 kinetically separable high-spin cytochromes. At −120 to −100°C, a rhombic signal appears, attributable to cytochrome d, followed at above −100°C, by appearance of a second, axial signal near g = 6, here assigned to cytochrome(s) b, and changes in the redox state of iron-sulphur clusters. The data kinetically resolve the 2 high-spin signals attributed to the oxidase complex and suggest schemes for electron flow to oxygen.

Cytochrome oxidase Escherichia coli Cytochrome b-d complex Bacterial electron transport Low-temperature technique     

Environmental and industrial applications of Yarrowia lipolytica

Yarrowia lipolytica is a fungus that degrades hydrophobic substrates very efficiently. The fungus displays several important characteristics that have encouraged researchers to study various basic biological and biotechnological applications in detail. Although the organism has been used as model system for studying dimorphism, salt tolerance, heterologous protein expression, and lipid accumulation, there are no recent reviews on the environmental and industrial applications of this organism. Included here are applications in bioremediation of environments contaminated with aliphatic and aromatic compounds, organic pollutants, 2,4,6-trinitrotoluene, and metals. A variety of industrially important recent processes for the synthesis of β-hydroxy butyrate, l-dopa, and emulsifiers have also been reviewed. Production of unique inherent enzymes (inulinases, α-mannosidases), novel applications of esterases and lipases, and the use of the fungus for heterologous expression of biotechnologically relevant products have also been highlighted. The review while entailing a general overview focuses critically on some of the recent advances on the applications of this yeast. The examples cited here demonstrate the use of wild-type, mutant as well as genetically manipulated strains of Y. lipolytica for the development of different products, processes, and technologies. This also throws light on how a single organism can be versatile with respect to its metabolic abilities and how it can be exploited for a variety of purposes. This review will thus form a base for future developments in this field.     

Molecular cloning and characterization of buffalo alpha(s1)-casein gene.

Buffaloes in Indian subcontinent play an important role as the producer of milk and milk products. The alpha(s1)-casein constitutes 38% of the total milk proteins. The present study was carried out to characterize the gene in Murrah breed of Riverine buffalo. Buffalo alpha(s1)-casein cDNA was synthesized by RT-PCR, then cloned using pDRIVE-cloning vector and sequenced. The sequencing revealed that the size of alpha(s1)-casein cDNA was of 645 bp with GC content of 45.58%. The alpha(s1)-casein gene coded 214 amino acids precursor with a signal peptide of 15 amino acid residues. The similarity of buffalo alpha(s1)-casein mRNA sequence with that of cattle, goat, sheep, pig, camel, equine and human were estimated as 97.2, 93, 92.3, 57.2, 59.5, 55.9 and 46.6%, respectively. A similar trend was observed when compared amino acid sequences of these species. In the phylogenetic trees, constructed from the data of the alpha(s1)-casein mRNA as well as protein sequences, it has been observed that buffalo, cattle, goat and sheep formed a cluster with a closer relationship between cattle and buffalo followed by goat and sheep.     

Prediction of Certain Well-Characterized Domains of Known Functions within the PE and PPE Proteins of Mycobacteria

The PE and PPE protein family are unique to mycobacteria. Though the complete genome sequences for over 500 M. tuberculosis strains and mycobacterial species are available, few PE and PPE proteins have been structurally and functionally characterized. We have therefore used bioinformatics tools to characterize the structure and function of these proteins. We selected representative members of the PE and PPE protein family by phylogeny analysis and using structure-based sequence annotation identified ten well-characterized protein domains of known function. Some of these domains were observed to be common to all mycobacterial species and some were species specific.