Mutant carotenoid deficient

Matsui, T., and Maruhashi, K., Isolation of Carotenoid-Deficient Mutant From Alkylated Dibenzothiophene Desulfurizing Nocardioform Bacteria, Gordonia Sp TM414. Current Microbiology, 2004. 48(2) pp. 130-134. 

The most photosensitive part of the coleoptile with respect to phototropism is the apical 50 qm-zone. The first millimeter of the tip is 160 times more sensitive than the second, and the second millimeter 1,800 times more sensitive than the third 108h In 1937, Bunning29 showed by microchemical method that there is a high concentration of carotenoid (lutein) below the tip of the avena coleoptile, from 250 jum to 2 mm below this point and just in the extreme tip no carotenoid is found. This calls in question whether the enormous local differences in sensitivity can solely be caused by corresponding different absorption gradients. This doubt is further substantiated by the fact, that carotenoid deficient mutants (containing 5 to 10% of the normal siblings) show normal phototropic sensitivity. 

This conclusion drawn by Castle and Shropshire was rejected by Jaffe94). He presented a theoretical analysis showing that the light lost by reflection at the surface is precisely compensated by light retained inside the sporangiophore by internal reflection. On the basis of several carotenoid deficient mutants, Jesaitis96) recently... 

A. Mutants with Deficient or Changed Carotenoid Compositions. 125... 

Mutants of Scenedesmus obliquus have been desaibed that are carotenoid-deficient when grown in the dark because of a lack of phytoene synthase activity (Sandmaim et al, 1997). These mutants behave differently from the Chlamydomonas mutants in that they assemble a functional PS I but no PS II and no Chi a/b complexes (Humbeck et al., 1989 Romer et al., 1995). Upon illumination, carotenoids are formed and, concomitantly, PS II activity and light-harvesting complexes appear (Romer et al.,... 

Chlamydomonas seems to be more similar to Scenedesmus than to Arabidopsis with respect to the consequences of j3-e carotenoid deficiency. In the lutl mutant, an increased Chi a b ratio indicates a partial defect in the assembly or stability of Chi a/b complexes (Eichenberger et al, 1986). However, at least some of the LHCII subunits are still assembled. Since these complexes are thought to contain lutein in the wildtype, this means that /S-carotene-type xanthophylls are probably able to replace lutein during the assembly and in stabilizing these complexes (Niyogi et al., 1997b). 

Of course, the interaction between the membrane-spanning helices A and B that is presumably stabilized by these carotenoids may in turn influence the trimer formation of the complex. However, it is also possible that the additional carotenoid(s), known to be part of the complex from biochemical data but not visible in the crystal stmcture, stabilize trimers. This can be suggested from the observation that in the aba mutant of Arabidopsis where zeaxanthin appears to replace violaxanthin and neoxanthin, the major LHCII dissociates more easily into monomers when isolated under partially denaturing conditions (Tardy and Havaux, 1996). A closer biochemical inspection of the major LHCII in various carotenoid-deficient plant and algae mutants will be necessary to assess the impact of carotenoids on the formation of trimeric LHCII. Another experimental approach will be to study how the variation of the carotenoid components influences the reconstitution of trimeric LHCII in vitro (Hobe et al, 1994). 

Eichenberger W, Boschetti A and Michel HP (1986) Lipid and pigment composition of a chlorophyll h-deficient mutant of Chlamydomonas reinhardttii. Physiol Plant 66 589-594 Ermler U, Fritzsch G, Buchanan SK and Michel H (1994) Structure of the photosynthetic reaction centre from Rhodobacter sphaeroides at 2,65 A resolution Cofactors and protein-cofactor interactions. Structure 2 925-936 Foidl M, Golecki JR and Oelze J (1997) Phototrophic growth and chlorosome formation in Chloroflexus aurantiacus under conditions of carotenoid deficiency. Photosynth Res 54 219-226... 

Sandmann G (1994) Carotenoid biosynthesis in microorganisms and plants. Eur J Biochem 223 7-24 Sandmann G, Bishop NI and Senger H (1997) The carotenoid deficient mutant, C 6E, of Scenedesmus obliquus is blocked at the site of phytoene synthase. Physiol Plant 99 391-394 Schmid VHR, Cammarata KV, Bruns BU and Schmidt GW... 

Many of the maize viviparous mutants are carotenoid deficient and have phenotypes that are not related to ABA levels. However, the vp8 mutant, which is probably blocked... 

Rakhimberdieva, M. G., I. N. Stadnichuk, I. V. Elanskaya, and N. V. Karapetyan (2004). Carotenoid-induced quenching of the phycobilisome fluorescence in photosystem II-deficient mutant of Synechocystis sp. FEBS Lett 574(1-3) 85-88. 

Prior to 1995, only one locus affecting Xanthophyll biosynthesis in photosynthetic tissues of Arabidopsis had been identified, the ABA i locus, the mutation of which disrupts zeaxanthin deepoxidase, one of two xanthophyll cycle enzymes (Koomneef et al, 1982 Rock and Zeevaart, 1991 Rock et al., 1992). As a step toward advancing understanding of xanthophyll biosynthesis, incorporation, and function in plants, the author s laboratory has screened for and identified mutations defining two additional loci required for xanthophyll biosynthesis in Arabidopsis, LUTl and LUT2 LUT= LUTein deficient). Mutations at either locus result in defects in the synthesis of lutein, the most predominant xanthophyll in plants. Singly and in combination with the aba mutation, these lut mutations have allowed the genetic construction of five distinct mutant lines which differ dramatically in their carotenoid composition relative to wild-type Arabidopsis. In the remainder of this chapter I will first briefly discuss the aba mutation followed by a... 

Humbeck K, Romer S and Senger H (1989) Evidence for an essential role of carotenoids in the assembly of an active photosystem 11. Planta 179 242-250 Hurry VM (1995) Non-photochemical quenching in xanthophyU cycle mutants of Arabidopsis and tobacco deficient in cytochrome B JF and ATPase activity. In Mathis P (ed) Photosynthesis From Light to Biosphere, pp 417-420. Kluwer Academic Publishers, Dordrecht Hurry V, Anderson JM, Chow WS and Osmond CB (1997) Accumulation of Zeaxanthin in absdsic acid-deficient mutants of Arabidopsis does not affect chlorophyll fluorescence quenching or sensitivity to photoinhibition in vivo. Plant Physiol 113 639-648... 

Chlamydomonas mutants that are entirely deficient in colored carotenoids do not accumulate reaction centers or light-harvesting complexes of Photosystem I or Photosystem II (Herrin et al., 1992). The accumulation of the mRNAs does not seem to be affected, so the failure in protein accumulation must be either due to inhibition of translation or rapid degradation of the proteins that cannot be assembled in the absence of carotenoids. Chi is also synthesized but very rapidly degraded in these mutants. 

Falbel TG, Staehelin LA and Adams WW III (1994) Analysis of xanthophyll cycle carotenoids and chlorophyll fluorescence in light intensity-dependent chlorophyll-deficient mutants of wheat and barley. Photosynth Res 42 , 191-202... 

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