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Author NameShen, Zhiyuan
Email Address zyshen at wpi.edu
TitlePhylogenetic Characterization of the Kinesin Superfamily and Functional Analysis of PpKin14-Vs in Physcomitrella patens
DepartmentBiology & Biotechnology
  • Vidali, Luis , Advisor
  • Duffy, Joseph B., Committee Member
  • Ryder, Elizabeth F., Committee Member
  • Tuzel, Erkan, Committee Member
  • Keywords
  • gene knockout
  • phylogenetic analysis
  • kinesin
  • microtubule
  • intracellular motility
  • PpKinesin14-Vs
  • chloroplast photorelocation
  • moss
  • Date of Presentation/Defense2014-01-07
    Availability restricted


    Chloroplasts are organelles that convert light

    energy to chemical energy through

    photosynthesis. The movement of chloroplasts

    within the cell for the optimization of light

    absorption is crucial for plant survival. Cellular

    motor proteins and cytoskeletal tracks

    can facilitate transport of organelles. As an

    ancient superfamily of microtubule-dependent

    motors, kinesins participate in various cellular

    activities including cytokinesis, vesicle

    and organelle movements. Based on phylogenetic

    relationships and functional analysis,

    the kinesin superfamily has been subdivided into

    more than 14 families, most of which

    can be found in plants. With the ever increasing

    amount of genomic information, it is

    important and beneficial to systematically

    characterize and document kinesins within an

    organism. As a result of my collaborative work

    with other members of the Vidali lab, a

    detailed phylogenetic characterization of the 76

    kinesins of the kinesin superfamily in the

    moss Physcomitrella patens is reported here. We

    found a remarkable conservation of

    families and subfamily classes with Arabidopsis,

    which is important for future

    comparative analyses of functions. Some of the

    families are composed of fewer members,

    while other families are greatly expanded in moss.

    To improve the comparison between

    species, and to simplify communication between

    research groups, we proposed a

    classification of subfamilies based on our

    phylogenetic analysis. As part of my efforts in

    studying chloroplasts motility, I investigated the

    function of two members of

    Physcomitrella kinesin family 14 class V proteins,

    Ppkin14-Va and -Vb. These two

    proteins are orthologs of the Arabidopsis KAC

    proteins which mediate actin-based

    chloroplast movement in Arabidopsis thaliana. In

    contrast, in the Physcomitrella both

    actin filaments (AFs) and microtubules (MTs)

    participate in chloroplast movement. Our

    results show that Ppkin14-Vs are important for

    maintaining chloroplast dispersion. They

    also function during chloroplast light avoidance

    responses via an AF-dependent, rather

    than MT-dependent mechanism. Although two Ppkin14-

    Vs do not act as MT-based

    motors, our phylogenetic study on moss kinesins

    provides an important source of

    information to track other potential kinesins that

    are predicted to move chloroplasts on


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