Identification and Characterization of a Ca2+-Dependent Actin Filament-Severing Protein from Lily Pollen

  • Xiaoxue Fan
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H
  • Jian Hou
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H
  • Xiaoliang Chen
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H
  • Faisal Chaudhry
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H
  • Christopher J. Staiger
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H
  • Haiyun Ren
    College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China (X.F., J.H., X.C., H.R.); Department of Biological Sciences and the Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and The State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China (H

抄録

<jats:title>Abstract</jats:title><jats:p>It is well known that a tip-focused intracellular Ca2+ gradient and the meshwork of short actin filaments at the tip region are necessary for pollen tube growth. However, little is known about the connections between the two factors. Here, a novel Ca2+-dependent actin-binding protein with molecular mass of 41 kD from lily (Lilium davidii) pollen (LdABP41) was isolated and purified with DNase I chromatography. Our purification procedure yielded about 0.6 mg of LdABP41 with &gt;98% purity from 10 g of lily pollen. At least two isoforms with isoelectric points of 5.8 and 6.0 were detected on two-dimensional gels. The results of N-terminal sequencing and mass-spectrometry analysis of LdABP41 showed that both isoforms shared substantial similarity with trumpet lily (Lilium longiflorum) villin and other members of the gelsolin superfamily. Negative-stained electron microscope images showed that LdABP41 severed in vitro-polymerized lily pollen F-actin into short actin filaments in a Ca2+-sensitive manner. Microinjection of the anti-LdABP41 antibody into germinated lily pollen demonstrated that the protein was required for pollen tube growth. The results of immunolocalization of the protein showed that it existed in the cytoplasm of the pollen tube, especially focused in the tip region. Our results suggest that LdABP41 belongs to the gelsolin superfamily and may play an important role in controlling actin organization in the pollen tube tip by responding to the oscillatory, tip-focused Ca2+ gradient.</jats:p>

収録刊行物

  • Plant Physiology

    Plant Physiology 136 (4), 3979-3989, 2004-12-01

    Oxford University Press (OUP)

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