Pollen profilin function depends on interaction with proline-rich motifs

• Published in: The Plant cell Vol. 10; no. 6; pp. 981 - 993
• Main Authors: Gibbon, B.C. (Purdue University, West Lafayette, IN.), Zonia, L.E, Kovar, D.R, Hussey, P.J, Staiger, C.J
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Physiologists 01.06.1998
• Subjects: ACTIN; ACTINA; ACTINE; Actins; Actins - metabolism; ADN; Amino Acid Sequence; AMINO ACID SEQUENCES; ANDROCEE; ANDROCEO; ANDROECIUM; ARN MENSAJERO; ARN MESSAGER; BINDING; BINDING PROTEINS; Binding Sites; Cell Nucleus - physiology; CHEMICAL COMPOSITION; Cloning, Molecular; COMPLEMENTARY DNA; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Contractile Proteins; Corn; DNA; ENDOSPERM; ENDOSPERMA; ENDOSPERME; Escherichia coli; EXPRESION GENICA; EXPRESSION DES GENES; Fluorescence; GENBANK/AF032370; GENE EXPRESSION; Hair cells; MESSENGER RNA; Microfilament Proteins - biosynthesis; Microfilament Proteins - chemistry; Microfilament Proteins - metabolism; MOLECULAR SEQUENCE DATA; MUTANT; MUTANTES; MUTANTS; NUCLEOTIDE SEQUENCE; nucleotide sequences; OPEN READING FRAMES; PEPTIDE; PEPTIDES; Peptides - metabolism; PEPTIDOS; Plant cells; PLANT PROTEINS; Plant Proteins - chemistry; Plant Proteins - metabolism; POLEN; POLLEN; Pollen - physiology; Pollen tubes; POLY-L-PROLINE; Polymerase Chain Reaction; POLYPEPTIDES; Profilins; Proline; Protein Binding; Protein isoforms; PROTEINAS; PROTEINAS AGLUTINANTES; PROTEINE; PROTEINE DE LIAISON; PROTEINS; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; SECUENCIA NUCLEOTIDICA; Sequence Alignment; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; STAMENS; Transcription, Genetic; ZEA MAYS; Zea mays - physiology
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.10.6.981

The actin binding protein profilin has dramatic effects on actin polymerization in vitro and in living cells. Plants have large multigene families encoding profilins, and many cells or tissues can express multiple profilin isoforms. Recently, we characterized several profilin isoforms from maize pollen for their ability to alter cytoarchitecture when microinjected into living plant cells and for their association with poly-L-proline and monomeric actin from maize pollen. In this study, we characterize a new profilin isoform from maize, which has been designated ZmPRO4, that is expressed predominantly in endosperm but is also found at low levels in all tissues examined, including mature and germinated pollen. The affinity of ZmPRO4 for monomeric actin, which was measured by two independent methods, is similar to that of the three profilin isoforms previously identified in pollen. In contrast, the affinity of ZmPRO4 for poly-L-proline is nearly twofold higher than that of native pollen profilin and the other recombinant profilin isoforms. When ZmPRO4 was microinjected into plant cells, the effect on actin-dependent nuclear position was significantly more rapid than that of another pollen profilin isoform, ZmPRO1. A gain-of-function mutant (ZmPRO1-Y6F) was created and found to enhance poly-L-proline binding activity and to disrupt cytoarchitecture as effectively as ZmPRO4. In this study, we demonstrate that profilin isoforms expressed in a single cell can have different effects on actin in living cells and that the poly-L-proline binding function of profilin may have important consequences for the regulation of actin cytoskeletal dynamics in plant cells.