Heat-stress response of maize mitochondria.
We have identified maize (Zea mays L. inbred B73) mitochondrial homologs of the Escherichia coli molecular chaperones DnaK (HSP70) and GroEL (cpn60) using two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblots. During heat stress (42 degrees C for 4 h), levels of HSP70 and cpn60 proteins did not change significantly. In contrast, levels of two 22-kD proteins increased dramatically (HSP22). Monoclonal antibodies were developed to maize HSP70, cpn60, and HSP22. The monoclonal antibodies were characterized with regard to their cross-reactivity to chloroplastic, cytosolic, and mitochondrial fractions, and to different plant species. Expression of mitochondrial HSP22 was evaluated with regard to induction temperature, time required for induction, and time required for degradation upon relief of stress. Maximal HSP22 expression occurred in etiolated seedling mitochondria after 5 h of a +13 degrees C heat stress. Upon relief of heat stress, the HSP22 proteins disappeared with a half-life of about 4 h and were undetectable after 21 h of recovery. Under continuous heat-stress conditions, the level of HSP22 remained high. A cDNA for maize mitochondrial HSP22 was cloned and extended to full length with sequences from an expressed sequence tag database. Sequence analysis indicated that HSP22 is a member of the plant small heat-shock protein superfamily.
Lund
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School of Biological Sciences and the Center for Biotechnology, University of Nebraska, Lincoln, Nebraska 68588-0118, USA.
Blum
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Bhattramakki
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Elthon
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D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D001483:Base Sequence; D018834:Chaperonin 60 / Q000276:immunology; D002736:Chloroplasts / Q000276:immunology; D003593:Cytoplasm / Q000276:immunology; D018076:DNA, Complementary / Q000032:analysis / Q000302:isolation & purification; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000276:immunology; D018869:Heat-Shock Response / Q000276:immunology / Q000502:physiology*; D051379:Mice; D008928:Mitochondria / Q000276:immunology / Q000502:physiology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000096:biosynthesis / Q000276:immunology; D016133:Polymerase Chain Reaction; D011817:Rabbits; D017422:Sequence Analysis, DNA; D013367:Submitochondrial Particles / Q000276:immunology; D013696:Temperature; D013997:Time Factors; D003313:Zea mays / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D000911:Antibodies, Monoclonal; D018834:Chaperonin 60; D018076:DNA, Complementary; C096801:HSP22 protein, plant; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D010940:Plant Proteins