Life Sciences Commons^™

Mechanisms For Regulation Of Plant Kinesins, Anindya Ganguly, Ram Dixit

Biology Faculty Publications & Presentations

Throughout the eukaryotic world, kinesins serve as molecular motors for the directional transport of cellular cargo along microtubule tracks. Plants contain a large number of kinesins that have conserved as well as specialized functions. These functions depend on mechanisms that regulate when, where and what kinesins transport. In this review, we highlight recent studies that have revealed conserved modes of regulation between plant kinesins and their non-photosynthetic counterparts. These findings lay the groundwork for understanding how plant kinesins are differentially engaged in various cellular processes that underlie plant growth and development.

Microtubule Severing At Crossover Sites By Katanin Generates Ordered Cortical Microtubule Arrays In Arabidopsis, Quan Zhang, Erica Fishel, Tyler Bertroche, Ram Dixit

Biology Faculty Publications & Presentations

Highlights

• Severing primarily depolymerizes the overlying CMT at crossover sites
• Severing probability increases nonlinearly with crossover time
• Katanin localizes to crossover sites and is required for severing
• Loss of katanin activity prevents the formation of coaligned CMT arrays

Summary
The noncentrosomal cortical microtubules (CMTs) of land plants form highly ordered parallel arrays that mediate cell morphogenesis by orienting cellulose deposition [1, 2 and 3]. Since new CMTs initiate from dispersed cortical sites at random orientations [4], parallel array organization is hypothesized to require selective pruning of CMTs that are not in the dominant orientation. Severing of CMTs at crossover sites …

The System I And System Iii Holocytochrome C Synthases In Cytochrome C Biogenesis, Brian San Francisco

All Theses and Dissertations (ETDs)

Cytochromes c are proteins that are involved in important redox reactions in organisms from every kingdom of life. C-type cytochromes, uniquely, possess a covalently bound heme. Since cytochromes c are assembled at their site(s) of function: outside of the cytoplasmic membrane in bacteria, in the chloroplast lumen, or in the mitochrondrial intermembrane space), their assembly poses unique challenges to heme trafficking and post translational modification. Three major systems exist in nature for cytochrome c assembly, termed systems I, II, and III. Using recombinant Escherichia coli, aspects of systems I and III were analyzed, with an emphasis on the synthase protein(s) …

Mscs-Like Mechanosensitive Channels In Plants And Microbes, Margaret E. Wilson, Grigory Maksaev, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

The challenge of osmotic stress is something all living organisms must face as a result of environmental dynamics. Over the past three decades, innovative research and cooperation across disciplines have irrefutably established that cells utilize mechanically gated ion channels to release osmolytes and prevent cell lysis during hypoosmotic stress. Early electrophysiological analysis of the inner membrane of Escherichia coli identified the presence of three distinct mechanosensitive activities. The subsequent discoveries of the genes responsible for two of these activities, the mechanosensitive channels of large (MscL) and small (MscS) conductance, led to the identification of two diverse families of mechanosensitive channels. …

Role Of Nucleation In Cortical Microtubule Array Organization: Variations On A Theme, Erica A. Fishel, Ram Dixit

Biology Faculty Publications & Presentations

The interphase cortical microtubules (CMTs) of plant cells form strikingly ordered arrays in the absence of a dedicated microtubule-organizing center. Considerable research effort has focused on activities such as bundling and severing that occur after CMT nucleation and are thought to be important for generating and maintaining ordered arrays. In this review, we focus on how nucleation affects CMT array organization. The bulk of CMTs are initiated from γ-tubulin-containing nucleation complexes localized to the lateral walls of pre-existing CMTs. These CMTs grow either at an acute angle or parallel to the pre-existing CMT. Although the impact of microtubule-dependent nucleation is …

Plant Cytoskeleton: Della Connects Gibberellins To Microtubules, Ram Dixit

Biology Faculty Publications & Presentations

A new study reveals that DELLA proteins directly interact with the prefoldin complex, thus regulating tubulin subunit availability in a gibberellin-dependent manner. This finding provides a mechanistic link between the growth-promoting plant hormone gibberellin and cortical microtubule organization.