Immunogold Localization of Intra- and Extra-Cellular Proteins and Polysaccharides of Plant Cells

This paper illustrates post-embedding immunogold labelling of protein and polysaccharide molecules of plant cells. For EM studies, one is restricted (for most plant cells) to the post-embedding approach because the surrounding cell wall prevents access of antibodies (and secondary gold-tagged markers) to internal sites. The large size of many plant cells also does not lend itself to diffusional entry of antibodies. The molecules localized include seed storage proteins that are large and present in major quantities, a smaller less abundant, water soluble albumin, an oxygen-binding protein, components of the photosynthetic electron transport chain, and complex sugars from the cell wall. A range of preparative procedures and embedding plastics are used

Sequence of two tomato nuclear genes encoding chlorophyll a/b -binding proteins of CP24, a PSII antenna component

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43424/1/11103_2004_Article_BF00017734.pd

Introduction of Genetically Engineered Organisms - Draft Programmatic Environmental Impact Statement—July 2007

The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) regulates the environmental introduction of genetically engineered (GE) organisms, including crop and noncrop plants, vertebrate and invertebrate animals, and micro-organisms. APHIS regulations are grounded in the most up-to-date science and are designed to provide a level of oversight appropriate for the safe introduction of GE organisms. APHIS is considering whether revisions to its regulations are necessary. One purpose of such revisions would be to address current and future technological trends resulting in GE plants with which the agency is less familiar, such as plants with environmental stress tolerance or enhanced nutrition, and plants engineered for new purposes such as biofuels or for production of pharmaceutical or industrial compounds. Additionally, the regulations would be revised to ensure a high level of environmental protection, to create regulatory processes that are transparent to stakeholders and the public, to consider the efficient use of agency resources, to ensure that the level of oversight is commensurate with the risk, and to ensure conformity with obligations under international treaties and agreements, such as World Trade Organization (WTO) agreements. To this end, this draft environmental impact statement (DEIS) was prepared to provide agency decisionmakers with a full range of regulatory alternatives and assist them in selecting a preferred alternative

Chlorophyll a/b binding (CAB) polypeptides of CP29, the internal chlorophyll a/b complex of PSII: characterization of the tomato gene encoding the 26 kDa (type 1) polypeptide, and evidence for a second CP29 polypeptide

CP29, the core chlorophyll a/b (CAB) antenna complex of Photosystem II (PSII), has two nuclearencoded polypeptides of approximately 26 and 28 kDa in tomato ( Lycopersicon esculentum ). Cab9, the gene for the Type 1 (26 kDa) CP29 polypeptide was cloned by immunoscreening a tomato leaf cDNA library. Its identity was confirmed by sequencing tryptic peptides from the mature protein. Cab9 is a single-copy gene with five introns, the highest number found in a CAB protein. In vitro transcription-translation gave a 31 kDa precursor which was cleaved to about 26 kDa after import into isolated tomato chloroplasts. The Cab9 polypeptide has the two highly conserved regions common to all CAB polypeptides, which define the members of this extended gene family. Outside of the conserved regions, it is only slightly more closely related to other PSII CABs than to PSI CABs. Sequence analysis of tryptic peptides from the Type II (28 kDa) CP29 polypeptide showed that it is also a member of the CAB family and is very similar or identical to the CP29 polypeptide previously isolated from spinach. All members of the CAB family have absolutely conserved His, Gln and Asn residues which could ligate the Mg atoms of the chlorophylls, and a number of conserved Asp, Glu, Lys and Arg residues which could form H-bonds to the polar groups on the porphyrin rings. The two conserved regions comprise the first and third predicted trans-membrane helices and the stroma-exposed segments preceding them.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47577/1/438_2004_Article_BF00259681.pd

Hypothesis for the evolution of three-helix Chl a/b and Chl a/c light-harvesting antenna proteins from two-helix and four-helix ancestors

The nuclear-encoded Chl a/b and Chl a/c antenna proteins of photosynthetic eukaryotes are part of an extended family of proteins that also includes the early light-induced proteins (ELIPs) and the 22 kDa intrinsic protein of PS II (encoded by psb S gene). All members of this family have three transmembrane helices except for the psb S protein, which has four. The amino acid sequences of these proteins are compared and related to the three-dimensional structure of pea LHC II Type I (Kühlbrandt and Wang, Nature 350: 130–134, 1991). The similarity of psb S to the three-helix members of the family suggests that the latter arose from a four-helix ancestor that lost its C-terminal helix by deletion. Strong internal similarity between the two halves of the psb S protein suggests that it in turn arose as the result of the duplication of a gene encoding a two-helix protein. Since psb S is reported to be present in at least one cyanobacterium, the ancestral four-helix protein may have been present prior to the endosymbiotic event or events that gave rise to the photosynthetic eukaryotes. The Chl a/b and Chl a/c antenna proteins, and the immunologically-related proteins in the rhodophytes may have had a common ancestor which was present in the early photosynthetic eukaryotes, and predated their division into rhodophyte, chromophyte and chlorophyte lineages. The LHC I-LHC II divergence probably occurred before the separation of higher plants from chlorophyte algae and euglenophytes, and the different Types of LHC I and LHC II proteins arose prior to the separation of angiosperms and gymnosperms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43538/1/11120_2004_Article_BF00029382.pd