Torti S.V.,Microbial and Structural Biology |
Torti F.M.,University of Connecticut Health Center
Nature Reviews Cancer | Year: 2013
Iron is an essential nutrient that facilitates cell proliferation and growth. However, iron also has the capacity to engage in redox cycling and free radical formation. Therefore, iron can contribute to both tumour initiation and tumour growth; recent work has also shown that iron has a role in the tumour microenvironment and in metastasis. Pathways of iron acquisition, efflux, storage and regulation are all perturbed in cancer, suggesting that reprogramming of iron metabolism is a central aspect of tumour cell survival. Signalling through hypoxia-inducible factor (HIF) and WNT pathways may contribute to altered iron metabolism in cancer. Targeting iron metabolic pathways may provide new tools for cancer prognosis and therapy. © 2013 Macmillan Publishers Limited. All rights reserved.
Griffiths K.K.,Microbial and Structural Biology |
Zhang J.,University of Connecticut Health Center |
Cowan A.E.,Microbial and Structural Biology |
Cowan A.E.,University of Connecticut Health Center |
And 2 more authors.
Molecular Microbiology | Year: 2011
Dormant bacterial spores are extraordinarily resistant to environmental insults and are vectors of various illnesses. However, spores cannot cause disease unless they germinate and become vegetative cells. The molecular details of initiation of germination are not understood, but proteins essential in early stages of germination, such as nutrient germinant receptors (GRs) and GerD, are located in the spore inner membrane. In this study, we examine how these germination proteins are organized in dormant Bacillus subtilis spores by expressing fluorescent protein fusions that were at least partially functional and observing spores by fluorescence microscopy. We show that GRs and GerD colocalize primarily to a single cluster in dormant spores, reminiscent of the organization of chemoreceptor signalling complexes in Escherichia coli. GRs require all their subunits as well as GerD for clustering, and also require diacylglycerol addition to GerD and GRs' C protein subunits. However, different GRs cluster independently of each other, and GerD forms clusters in the absence of all the GRs. We predict that the clusters represent a functional germination unit or 'germinosome' in the spore inner membrane that is necessary for rapid and cooperative response to nutrients, as conditions known to block nutrient germination also disrupt the protein clusters. © 2011 Blackwell Publishing Ltd.