ORCID Profile
0000-0002-3364-0931
Current Organisation
Wake Forest University
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Publisher: American Society for Microbiology
Date: 06-2003
DOI: 10.1128/IAI.71.6.3000-3009.2003
Abstract: During the process of bloodfeeding by Anopheles stephensi , mammalian latent transforming growth factor β1 (TGF-β1) is ingested and activated rapidly in the mosquito midgut. Activation may involve heme and nitric oxide (NO), agents released in the midgut during blood digestion and catalysis of l- arginine oxidation by A. stephensi NO synthase (AsNOS). Active TGF-β1 persists in the mosquito midgut to extended times postingestion and is recognized by mosquito cells as a cytokine. In a manner analogous to the regulation of vertebrate inducible NO synthase and malaria parasite ( Plasmodium ) infection in mammals by TGF-β1, TGF-β1 regulates AsNOS expression and Plasmodium development in A. stephensi . Together, these observations indicate that, through conserved immunological cross talk, mammalian and mosquito immune systems interface with each other to influence the cycle of Plasmodium development.
Publisher: American Chemical Society (ACS)
Date: 10-09-2005
DOI: 10.1021/BI051257I
Abstract: NifU is a homodimeric modular protein comprising N- and C-terminal domains and a central domain with a redox-active [2Fe-2S](2+,+) cluster. It plays a crucial role as a scaffold protein for the assembly of the Fe-S clusters required for the maturation of nif-specific Fe-S proteins. In this work, the time course and products of in vitro NifS-mediated iron-sulfur cluster assembly on full-length NifU and truncated forms involving only the N-terminal domain or the central and C-terminal domains have been investigated using UV-vis absorption and Mössbauer spectroscopies, coupled with analytical studies. The results demonstrate sequential assembly of labile [2Fe-2S](2+) and [4Fe-4S](2+) clusters in the U-type N-terminal scaffolding domain and the assembly of [4Fe-4S](2+) clusters in the Nfu-type C-terminal scaffolding domain. Both scaffolding domains of NifU are shown to be competent for in vitro maturation of nitrogenase component proteins, as evidenced by rapid transfer of [4Fe-4S](2+) clusters preassembled on either the N- or C-terminal domains to the apo nitrogenase Fe protein. Mutagenesis studies indicate that a conserved aspartate (Asp37) plays a critical role in mediating cluster transfer. The assembly and transfer of clusters on NifU are compared with results reported for U- and Nfu-type scaffold proteins, and the need for two functional Fe-S cluster scaffolding domains on NifU is discussed.
Publisher: American Society for Microbiology
Date: 15-07-2009
DOI: 10.1128/JB.00504-09
Abstract: Azotobacter vinelandii is a soil bacterium related to the Pseudomonas genus that fixes nitrogen under aerobic conditions while simultaneously protecting nitrogenase from oxygen damage. In response to carbon availability, this organism undergoes a simple differentiation process to form cysts that are resistant to drought and other physical and chemical agents. Here we report the complete genome sequence of A. vinelandii DJ, which has a single circular genome of 5,365,318 bp. In order to reconcile an obligate aerobic lifestyle with exquisitely oxygen-sensitive processes, A. vinelandii is specialized in terms of its complement of respiratory proteins. It is able to produce alginate, a polymer that further protects the organism from excess exogenous oxygen, and it has multiple duplications of alginate modification genes, which may alter alginate composition in response to oxygen availability. The genome analysis identified the chromosomal locations of the genes coding for the three known oxygen-sensitive nitrogenases, as well as genes coding for other oxygen-sensitive enzymes, such as carbon monoxide dehydrogenase and formate dehydrogenase. These findings offer new prospects for the wider application of A. vinelandii as a host for the production and characterization of oxygen-sensitive proteins.
No related grants have been discovered for Patricia Dos Santos.