Staff member

Understanding how charges move through and between biomolecules is a fundamental question that constitutes the basis for many biological processes. On the other hand, it has potential applications in the design of sensors based on biomolecules and single molecule devices. In this review we introduce the study of the electron transfer (ET) process in biomolecules, providing an overview of the fundamental theory behind it and the different experimental approaches. The ET in proteins is introduced by reviewing a complete electronic characterization of a redox protein (azurin) using electrochemical scanning tunnelling microscopy (ECSTM). The ET process in DNA is overviewed and results from different experimental approaches are discussed. Finally, future directions in the study of the ET process in biomolecules are introduced as well as examples of possible technological applications.

JTD Keywords: Bioelectrochemistry, Biomolecular electronics, Charge transfer, Nanobiodevice, Single-molecule junction

Citrus tristeza virus (CTV) causes one of the most destructive viral diseases of citrus worldwide. Generation of resistant citrus genotypes through genetic engineering could be a good alternative to control CTV. To study whether production of single-chain variable fragment (scFv) antibodies in citrus could interfere and immunomodulate CTV infection, transgenic Mexican lime plants expressing two different scFv constructs, separately and simultaneously, were generated. These constructs derived from the well-referenced monoclonal antibodies 3DF1 and 3CA5, specific against CTV p25 major coat protein, whose mixture is able to detect all CTV isolates characterized so far. ScFv accumulation levels were low and could be readily detected just in four transgenic lines. Twelve homogeneous and vigorous lines were propagated and CTV-challenged by graft inoculation with an aggressive CTV strain. A clear protective effect was observed in most transgenic lines, which showed resistance in up to 40-60% of propagations. Besides, both a delay in symptom appearance and attenuation of symptom intensity were observed in infected transgenic plants compared with control plants. This effect was more evident in lines carrying the 3DF1scFv transgene, being probably related to the biological functions of the epitope recognized by this antibody. This is the first report describing successful protection against a pathogen in woody transgenic plants by ectopic expression of scFv recombinant antibodies.

JTD Keywords: CTV control, Immunomodulation, Plantibodies, Recombinant antibodies, Transgenic citrus