Two new chimeric Bacillus thuringiensis (Bt) proteins, Cry1A.2 and Cry1B.2, were constructed using specific domains, which provide insecticidal activity against key lepidopteran soybean pests while minimizing receptor overlaps between themselves, current, and soon to be commercialized plant incorporated protectants (PIP's) in soybean.
View Article and Find Full Text PDFTwo new modified () proteins, Cry1Da_7 and Cry1B.868, with activity against fall armyworms (FAW), (J.E.
View Article and Find Full Text PDFInsect Biochem Mol Biol
February 2019
The development of insect resistance to pesticides via natural selection is an acknowledged agricultural issue. Likewise, resistance development in target insect populations is a significant challenge to the durability of crop traits conferring insect protection and has driven the need for novel insecticidal proteins (IPs) with alternative mechanism of action (MOA) mediated by different insect receptors. The combination or "stacking" of transgenes encoding different insecticidal proteins in a single crop plant can greatly delay the development of insect resistance, but requires sufficient knowledge of MOA to identify proteins with different receptor preferences.
View Article and Find Full Text PDFThe use of Bt proteins in crops has revolutionized insect pest management by offering effective season-long control. However, field-evolved resistance to Bt proteins threatens their utility and durability. A recent example is field-evolved resistance to Cry1Fa and Cry1A.
View Article and Find Full Text PDFThe need for sustainable insect pest control is driving the investigation and discovery of insecticidal proteins outside of the typical 3-domain Cry protein family from Bacillus thuringiensis (Bt). Examples include Cry35 and Cry51 that belong to protein families (Toxin_10, ETX_MTX2) sharing a common β-pore forming structure and function with known mammalian toxins such as epsilon toxin (ETX). Although β-pore forming proteins are related to mammalian toxins, there are key differences in sequence and structure that lead to organism specificity that is useful in the weight-of-evidence approach for safety assessment.
View Article and Find Full Text PDFThe cotton pests Lygus hesperus and Lygus lineolaris can be controlled by expressing Cry51Aa2.834_16 in cotton. Insecticidal activity of pore-forming proteins is generally associated with damage to the midgut epithelium due to pores, and their biological specificity results from a set of key determinants including proteolytic activation and receptor binding.
View Article and Find Full Text PDFLipoic acid is a sulfur-containing 8-carbon fatty acid that functions as a central cofactor in multienzyme complexes that are involved in the oxidative decarboxylation of glycine and several alpha-keto acids. In its functional form, it is bound covalently in an amide linkage to the epsilon-amino group of a conserved lysine residue of the "lipoyl bearing subunit," resulting in a long "swinging arm" that shuttles intermediates among the requisite active sites. In Escherichia coli and many other organisms, the lipoyl cofactor can be synthesized endogenously.
View Article and Find Full Text PDFStearoyl-ACP Delta9 desaturase (Delta9D) catalyzes the NADPH- and O(2)-dependent insertion of a cis double bond between the C9 and C10 positions of stearoyl-ACP (18:0-ACP) to produce oleoyl-ACP (18:1-ACP). This work revealed the ability of reduced [2Fe-2S] ferredoxin (Fd) to act as a catalytically competent electron donor during the rapid conversion of 18:0-ACP into 18:1-ACP. Experiments on the order of addition for substrate and reduced Fd showed high conversion of 18:0-ACP to 18:1-ACP (approximately 95% per Delta9D active site in a single turnover) when 18:0-ACP was added prior to reduced Fd.
View Article and Find Full Text PDFStearoyl-acyl carrier protein Delta(9)-desaturase (delta9D) catalyzes regio- and stereospecific insertion of cis double bonds into acyl chains attached to acyl carrier protein. Steady-state and stopped-flow fluorescence anisotropy measurements using acylated forms of dansyl- and fluoresceinyl-ACPs revealed equilibrium dissociation constants and dissociation rate constants for 16:0-, 17:0-, and 18:0-ACPs with resting and chemically 4e(-) reduced delta9D. Binding of 1 nM 18:0-fluoresceinyl-ACP to one subunit of the dimeric resting delta9D was observed with K(D1) = 13 +/- 3 nM.
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