Isolation and proteomic alalysis of cell wall-deficientHaematococcus pluvialis mutants

Abstract

The green alga Haematococcus pluvialis has a plant-like cell wall consisting of glycoproteins and cellulose that is modified during the cell cycle and under various conditions. These features allow Haematococcus to be used as a model organism for studying cell wall biology. Development of the Haematococcus model is hampered by the absence of mutants that could provide insight into the biosynthesis and assembly of wall components. Haematococcus mutants (WM#537 and WM#2978) (WM--wall mutant) with defective cell walls were obtained by chemical mutagenesis. WM#537 features a secondary wall of considerably reduced thickness, whereas WM#2978 possesses a somewhat reduced secondary wall with little intervening space between the wall and plasmalemma. 2-DE revealed that a majority of the cell wall proteins were present in the wild-type and mutant cell walls throughout the cell cycle. PMF identified 55 wall protein orthologs from these strains, including a subset of induced proteins known to be involved in wall construction, remodeling, and defense. Down-regulation of certain wall proteins in the two mutants was associated with the wall defects, whereas overexpression of other proteins may have compensated for the defective walls in the two mutants.

Ultrastructure and Composition of the Nannochloropsis gaditana Cell Wall

“…The wall comprises an outer algaenan layer protecting an inner cellulose layer. Many algae produce algaenan-containing cell walls, including vegetative cells of Scenedesmus, some Chlorella species, and all Nannochloropsis species tested (25,(77)(78)(79)(80)(81), cysts of Chlamydomonas, Haematococcus, and Polytomella (49,(82)(83)(84)(85)(86)(87)(88)(89), and Botryococcus colonies (126). In thin sections of osmicated, dehydrated specimens, the presence of algaenan usually (43) correlates with the presence of a layer called the trilaminar sheath (TLS), a narrow dark-light-dark domain at the wall periphery (2,77,80,81,83,88,90).…”

Astaxanthin in microalgae: pathways, functions and biotechnological implications

“…MT 2877 also accumulated 100% more astaxanthin, leading to a 4-fold increase in volumetric astaxanthin productivity compared to the wild type . Earlier, two H. pluvialis cell wall deficient mutants, MT 537 and MT 2978, have been generated by chemical mutagenesis (Wang et al 2005). Haematococcus wild type cells possess thick and rigid cell walls that reduce considerably the bioavailability of astaxanthin to human and animals if whole Haematococcus cells are consumed without cell disruption by chemical or physical means.…”

“…Production of astaxanthin using the cell wall mutants may also reduce downstream processing costs whereby eliminating or minimizing the cell wall disruption step which is otherwise required for wild type Haematococcus (Wang et al 2005, Hu et al 2006). Some mating-based breeding techniques can also be applied to Haematococcus to improve existing or introduce new desirable traits, given that many Haematococcus strains vary in photosynthesis efficiency, growth, astaxanthin content, and susceptibility to oxidative stress or parasite attack.…”

Differentially Secreted Proteins of Antarctic and Mesophilic Strains ofSynechocystis SalinaandChlorella Vulgarisafter UV-B and Temperature Stress Treatment

“…the green alga Haematococcus pluvialis has a plantlike cell wall consisting of glycoproteins and cellulose. cell wall proteome analysis of H. pluvialis and its cell wall mutants identified a subset of induced proteins known to be involved in wall reconstruction and defense (53,54). Baba et al (2) observed remarkable changes in the amount and composition of extracellular proteins after transfer of Chlamydomonas reinhardtii cells to 3 % co 2 .…”