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Evaluating the role of a multi‐heme cytochrome c in electron transfer from an electrode surface to Heliobacterium modesticaldum
Author(s) -
HerreraTheut Kathryn Ann,
Gisriel Christopher,
Laureanti Joseph,
Orf Gregory,
Baker Patricia,
Jones Anne Katherine,
Redding Kevin
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.913.13
Subject(s) - electron transfer , heme , cytochrome , gene , electron transport chain , redox , chemistry , organism , plasmid , hemeprotein , electrode , biology , biophysics , biochemistry , genetics , enzyme , photochemistry , organic chemistry
Heliobacterium modesticaldum (H. modesticaldum) is an anaerobic photoheterotroph that can produce H 2 when other electron transfer pathways are restricted. In addition, electrons can be injected into this organism via an electrode and redox mediator in a light‐dependent fashion, as shown recently by the Redding and Jones research groups. These factors make H. modesticaldum an ideal organism for use in a microbial photoelectrosynthesis cell, in which electricity can be used to power specific metabolic processes that produce a desired compound (e.g. H 2 ). However, the injection of electrons into this organism has not yet been optimized. There is a gene (HM1_0653) in the genome encoding a multi‐heme cytochrome c that is similar to the proteins known to be used for exit of electrons in the well‐known electrode‐respiring bacteria (e.g. Geobacteria ). RNA‐sequencing in the Redding lab has shown that the HM1_0653 gene is very poorly expressed in H. modesticaldum . Boosting expression of this cytochrome could lead to faster electron transfer into the cells and thereby more H 2 production. This hypothesis is being tested by cloning the HM1_0653 gene into a plasmid behind a strong promoter and introducing it into H. modesticaldum using a transformation system recently developed in the Redding lab. To test that the protein is being highly expressed, SDS‐PAGE/heme‐staining will be conducted. The effect of HM1_0653 on electron transfer will then be assessed by comparing the light‐dependent current into cells containing the overproducing plasmid with control cells, as well as H 2 production. Support or Funding Information I would like to thank Arizona Power Authority and the Arizona State University College of Liberal Arts and Sciences Scholarship for their support.