title: Proteomic profiling of maize opaque endosperm mutants reveals selective accumulation of lysine-enriched proteins.
abstract: Reduced prolamin (zein) accumulation and defective endoplasmic reticulum (ER) body formation occurs in maize opaque endosperm mutants opaque2 (o2), floury2 (fl2), defective endosperm*B30 (DeB30), and Mucronate (Mc), whereas other opaque mutants such as opaque1 (o1) and floury1 (fl1) are normal in these regards. This suggests that other factors contribute to kernel texture. A liquid chromatography approach coupled with tandem mass spectrometry (LC-MS/MS) proteomics was used to compare non-zein proteins of nearly isogenic opaque endosperm mutants. In total, 2762 proteins were identified that were enriched for biological processes such as protein transport and folding, amino acid biosynthesis, and proteolysis. Principal component analysis and pathway enrichment suggested that the mutants partitioned into three groups: (i) Mc, DeB30, fl2 and o2; (ii) o1; and (iii) fl1. Indicator species analysis revealed mutant-specific proteins, and highlighted ER secretory pathway components that were enriched in selected groups of mutants. The most significantly changed proteins were related to stress or defense and zein partitioning into the soluble fraction for Mc, DeB30, o1, and fl1 specifically. In silico dissection of the most significantly changed proteins revealed novel qualitative changes in lysine abundance contributing to the overall lysine increase and the nutritional rebalancing of the o2 and fl2 endosperm.
authors.affiliation: Department of Agronomy and Horticulture, Center for Plant Science Innovation, Beadle Center for Biotechnology, 1901 Vine Street, PO Box 880665, University of Nebraska, Lincoln, NE 68588-0665, USA.
authors.forename: Kyla J
authors.initials: KJ
authors.lastname: Morton
authors.affiliation: Department of Agronomy and Horticulture, Center for Plant Science Innovation, Beadle Center for Biotechnology, 1901 Vine Street, PO Box 880665, University of Nebraska, Lincoln, NE 68588-0665, USA.
authors.forename: Shangang
authors.initials: S
authors.lastname: Jia
authors.affiliation: School of Biological Sciences, Center for Plant Science Innovation, Beadle Center for Biotechnology, 1901 Vine Street, PO Box 880665, University of Nebraska, Lincoln, NE 68588-0665, USA.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Agronomy and Horticulture, Center for Plant Science Innovation, Beadle Center for Biotechnology, 1901 Vine Street, PO Box 880665, University of Nebraska, Lincoln, NE 68588-0665, USA dholding2@unl.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: Holding
mesh_terms: D016000:Cluster Analysis; D056625:Endosperm / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D058977:Molecular Sequence Annotation; D009154:Mutation / Q000235:genetics*; D010940:Plant Proteins / Q000378:metabolism*; D025341:Principal Component Analysis; D020543:Proteome / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D003313:Zea mays / Q000378:metabolism*; D015028:Zein / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D020543:Proteome; D015028:Zein; D008239:Lysine
keywords: Endosperm; maize; non-zein; opaque; proteome; stress.