THE LU LAB

Photosynthesis provides chemical energy for nearly all life forms on earth. The rising human population and increasing demand for food, fiber, and fuel generate needs for higher photosynthetic efficiency in crop plants. The Lu Laboratory uses genetic, genomic, biochemical, and physiological approaches to understand the import, assembly, and repair of photosynthetic proteins and complexes, as well as connections between photosynthesis and amino acid metabolism.

 

Five photosynthetic complexes exist in chloroplast thylakoid membranes: photosystem II (PSII), cytochrome b6f complex (Cyt b6f), photosystem I (PSI), ATP synthase, and NAD(P)H dehydrogenase (NDH) (Figure 1).

Figure 1. The transfer of electrons and protons in among five protein complexes in thylakoid membranes. H+, proton. e-, electron. Fd, ferredoxin. FNR, ferredoxin-NADP+ reductase. FQR, ferredoxin-plastoquinone reductase. OEC, oxygen evolving complex. PC, Plastocyanin. Pi, inorganic phosphate. PQ, plastoquinone. The blue dashed lines, red dashed lines, and yellow solid lines represent linear electron transfer, cyclic electron transfer, and proton movement, respectively.

Transcripts, proteins, and complexes invovled in photosynthetic light reactions undergo modifications and regulation (Figure 2). Like mitochondrial RNAs, plastid RNAs are subject to editing. In flowering plants, RNA editing converts specific cytidine (C) to Uridine (U) and it is important for restoring the functions of RNAs/proteins. Some photosynthetic proteins requires cofactors, such as Fe-S clusters, to function. Absence of co-factor binding causes reduced protein abundance and activities. Photosynthetic complexes are also subject to maintenance and repair, especially under adverse environments, to replenish worn proteins and complexes.

Figure 3. Photosynthesis provides precursors (carbohydrates), energy (ATP), and reducing power (e.g., NADPH) for amino acid biosynthesis.

Figure 2. Transcripts, proteins, and complexes involved in photosynthetic light reactions undergo modifications and regulation. Chl, chlorophyll. Fe-S, iron-sulfur clusters.

In plants, photosynthesis and the biosynthesis of many amino acids occur in chloroplasts. Photosynthesis provides precursors, energy, and reducing power for amino acid biosynthesis (Figure 3). In collaboration with Dr. Rob Last’s group at Michigan State University, the Lu Lab seeks to identify and understand novel connections between photosynthesis and amino acid metabolism. This is accomplished by phenotypic characterization and correlation network analysis of a large collection of insertion mutants. Mutants with robust and interesting phenotypes are selected for focused studies.

Examples of Focused Studies:

  • Functions of chloroplast stromal chaperone proteins in chloroplast protein import and thylakoid membrane integration

  • Evolution of a thylakoid zinc-finger protein during plants transition from water to land

  • Assembly and transfer of iron-sulfur clusters in chloroplasts and mitochondria

  • Plastid RNA editing

  • Regulation of biosynthetic pathways of aspartate-derived amino acids

 

Funding Sources:

  • National Sciences Foundation (MCB-1244008, PI: Yan Lu, Co-PI:  Rob Last)

  • WMU Support for Faculty Scholars Award (PI: Yan Lu)

  • WMU Research Development Award (PI: Yan Lu)

  • WMU Faculty Research and Creative Activities Award (W2012-001, PI: Yan Lu)

  • WMU Faculty Research and Creative Activities Award (W2016-023, PI: Yan Lu)

The Lu Laboratory:

  • Dr. Jun Zhao, postdoctoral visiting research associate

  • Audrey M. Searing, undergraduate student

 

Institutional Web Page about the Lu Lab

 

Google Scholar Profile of Dr. Yan Lu