John H. Law

Adjunct Professor
Entomology Department
University of Georgia
420 Biological Science Bldg
Athens, GA 30602

 

 

 

 

 

 

 


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Professional History:
 

Regents Professor of Biochemistry and Entomology, Department of Biochemistry and Molecular Biophysics, The University of Arizona, (retired 2003)
Ph.D. 1957, University of Illinois
Member, National Academy of Sciences, 1992
 

Research Interests

Iron metabolism in insects
Insect proteins, iron and lipid transport

Iron metabolism in insects is my research focus. Iron is an essential nutrient, but it is also a potent toxin, because it can catalyze oxidative reactions that are destructive to cells. Biology has designed ways to utilize iron while minimizing its toxic properties. Usually this involves production of molecules that can bind or sequester ferric ions in a form that will not catalyze oxidative reactions. Two important examples are a transport protein, transferrin, and a storage protein, ferritin. Transferrin is one member of a family of proteins that have various functions in vertebrates. Other members of this family are lactoferrin and ovotransferrin. These latter proteins serve to sequester ferric ions in a form that is unavailable as a nutrient for parasites or pathogens, and thus they constitute a part of the defense of the vertebrate against these agents.

Insects produce members of the transferrin family and ferritins, but in each case, significant differences exist between the insect forms and those of vertebrates or other organisms. While most vertebrate transferrins have two similar lobes, each with a site for binding ferric ion with high affinity (1020M.!), most insect transferrins have one functional lobe and one non-functional lobe that lacks an iron-binding site. On infection with bacteria or some parasites, the synthesis of insect transferrin is up regulated significantly. We believe that this is an iron-withholding defense strategy.

Insect ferritins resemble those of other organisms in size and shape huge, hollow spheres composed of 24 subunits of at least 2 distinct classes. However, while ferritins of other animals are cytoplasmic proteins used for storage of excess ferric ions, insect ferritins are secreted from and taken up by cells. Insect ferritin subunits are also larger than those of other organisms, and the intact ferritins are thus of higher molecular masses. From several insects, cDNA clones encoding ferritin subunits have been obtained, and in the case of Drosophila melanogaster, the gene structures have been determined. These differ significantly from the genes encoding the vertebrate proteins. Much remains to be done in order to understand the functions of insect ferritins.

selected Publications:
 

Missirlis F., Holmberg S., Georgieva T., Ddunkov, B.C., Rouault T.A., Law J.H. (2006) Characterization of mitochondrial ferritin in Drosophila. Proc. Natl. Acad. Sci. USA. 103, 5893-8.

Harizanova, N., Georgieva, T., Dunkov, B.C., Yoshiga, T., Law, J.H. (2005) Aedes aegypti transferrin. Gene structure, expression pattern, and regulation. Insect Mol. Biol. 14, 79-88.

Kopá?ek, P., ?dychová, J., Yoshiga , T., Weise, C., Rudenko, N. and Law, J.H. (2003) Molecular cloning, expression and isolation of ferritins from two tick species: Ornithodoros moubata and Ixodes ricinus . Insect Biochemistry and Molecular Biology, 33 , 103-13.

Paiva-Silva, G.O., Sorgine, M.H.F., Benedetti, C.E., Meneghini, R., Almeida, I.C., Machado, E.A., Dansa-Petretski, Yepiz-Plascencia, G.M., Law, J.H., Oliveira, P.L. and Masuda, H. (2002) On the biosynthesis of Rhodnius prolixis heme-binding protein. Insect Biochemistry and Molecular Biology, 32 , 1533-41.

Zdobnov, E.M., von Mering, C., Letunic, I., Torrents, D., Suyama, M., Copley, R.R., Christophides, G.K., Thomasova, D., Holt, R.A., Subrmanian, G.M., Mueller, H.-M., Dimopoulos, G., Law, J.H., Wells, M.A., Birney, E., Charlab, R., Halpern, A.L., Kokoza, E., Kraft, C.L., Lai, Zhongwu, Lewis, S., Louis, C., Barillas-Mury, C., Nusskern, D., Rubin, G.M., Salzberg, S.L., Sutton, G.G., Topalis, P., Wides, R., Wincker, P., Yandell, M., Collins, F.H., Ribeiro, J., Gelbart, W.M., Kafatos, F.C. and Bork, P. (2002) Comparative genome and proteome analysis of   Anopheles gambiae and Drosophila melanogaster . Science, 298 , 149-159.

Dunkov, B.C., Georgieva, T., Yoshiga, T., Hall, M., Law, J.H. 2002. Aedes aegypti ferritin heavy chain homologue: feeding of iron or blood influences message levels, lengths and subunit abundance. Journal of Insect Science, 2.7 (Available online: insectscience.org/2.7)

Law, J.H. (2002) Insects, oxygen and iron. Biochem. Biophys. Research Comm., 292 , 1191-5

Georgieva, T., Dunkov, B.C., Dimov, S., Ralchev, K. and Law, J.H. (2002)Drosophila melanogaster ferritin: cDNA encoding a light chain homologue, temporal and tissue specific expression of both subunit types. Insect Biochem. Mol. Biol. 32 , 295-302.

Nichol, H., Law, J.H.and Winzerling JJ. (2002) Iron metabolism in insects. Annu. Rev.Entomol. 47 , 535-59.

Dunkov, B.C., T. Georgieva, T. Yoshiga, M. Hall, and J.H. Law. 2002. Aedes aegypti ferritin heavy chain homologue: feeding of iron or blood influences message levels, lengths and subunit abundance. Journal of Insect Science , 2: 7-16.

Georgieva, T., B.C. Dunkov, S. Dimov, K. Ralchev, and J.H. Law. 2002. Drosophila melanogaster ferritin: cDNA encoding a light chain homologue, temporal and tissue specific expression of both subunit types. Insect Biochem. Mol. Biol . 32: 295-302

Wiegler, R., Willingham, L.A., Engler, D.L., Tolman, K.J., Bellows, D., Van der Horst, D.J., Yepiz-Plascencia, G.M. and Law, J.H. 1999. A novel lipoprotein form the hemolymph of the cochineal insect, Dactylopius confusus . Eur. J. Biochem. 260: 285-290.

Yoshiga, T., Georgieva, T., Dunkov, B.C., Harizanova, N., Ralchev, K. and Law, J.H. 1999. Drosophila melanogaster transferrin. Cloning, deduced protein sequence, expression during the life cycle, gene localization and up-regulation on bacterial infection. Eur. J. Biochem . 260: 414-420.

Georgieva, T., Dunkov, BC, Harizanova, N., Ralchev, K. and Law, J.H. 1999. Iron availability dramatically alters the distribution of ferritin subunit messages in Drosophila melanogaster . Proc. Natl. Acad. SCI, USA . 96: 2716-2721.

Pham, D.Q.-D., Winzerling, J.J., Dodson, M.S. and Law, J.H. 1999. Modulation of mosquito ferritin synthesis by iron: transcriptional and translational regulation. Eur. J. Biochem ., in press.

Kang, Y., Ziegler, R., VanAntwerpen, R., and Law, J.H. (1997) Characterization of the Solubilized Oocyte Membrane Receptor for Insecticyanin, a Hemolymph Biliprotein of the Hawkmoth Manduca sexta . Biochim. Biophys. Acta 1324: 285-295.

Winzerling, J.J. and Law, J.H. 1997. Comparative Nutrition of Iron and Copper. Annu. Rev. Nutr . 17: 501-526.

Charlesworth, A., Gospodov, I., Georgieva, T., Law, J. H., Dunkov, B. C., Ralcheva, N., Barillas-Mury, C., Ralchev, K. and Kafatos, F. C. (1997) Drosophila melanogaster ferritin. Isolation and properties, molecular cloning of a cDNA encoding one subunit, and localization of the gene on the third chromosome. Eur. J. Biochem . 247: 470-475.

Yoshiga, T., Hernandez, V.P., Fallon, A.M. and Law, J.H. 1997. Mosquito transferrin, an acute phase protein that is upregulated upon infection. Proc. Nat. Acad. Sci. USA 94: 12337-12342.

 


 

 

 

  
       

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