Chromoplasts of Tropaeolum majus L.: Isolation and characterization of lipoprotein elements

Abstract

Chromoplasts of unfolding petals of Tropaeolum majus contain large amounts of filaments (which, in sections, appear as tubules), and unevenshaped, isodiametric to elongated bodies (IBs). These structural elements are the major sites of the chromoplast pigments. They were freed from isolated chromoplasts and subjected to sucrose density gradient centrifugation. At a density of 1.080 g cm(-3) a distinct orange band contained almost exclusively fine filaments of 15-20 nm in diameter as shown after negative staining. Other filaments and most of the IBs were heterogeneous in size, shape, and density and were collected in two fractions of buoyant densities of 1.025 and 1.055 g cm(-3). The three fractions thus obtained comprise 15-33% protein, large amounts of carotenoids and their esters, glyco- and phospholipids, as well as minor amounts of tocopherols. A higher buoyant density of particles is correlated with a higher relative content of protein and glyco- and phospholipids and a lower relative content of carotenoids. The polypeptide pattern, as shown by SDS-polyacrylamide gel electrophoresis, is very similar in all three fractions. There is one main polypeptide, with a MW of about 30,000, accounting for up to 80% of the protein of each fraction.

A mechanism implicating plastoglobules in thylakoid disassembly during senescence and nitrogen starvation

“…The chromoplast fibrils not only contain apolar (carotenoids, tocopherol) and polar (galactolipids, phospholipids) lipids but also a dominant protein of 32 kD protein appropriately termed fibrillin (Deruere et al 1994). Proteins similar in size were previously identified in the fibrils of Japanese rose (Wuttke 1976), Nasturtium (Winkenbach et al 1976) and Palisota barteri (Knoth et al 1986). The same group of proteins was later termed plastid-lipid associated protein (PAP), because of its localization not only both in chromoplasts but also in chloroplast plastoglobules and its association with lipid-containing structures (PozuetaRomero et al 1997).…”

Xanthophyll biosynthesis in chromoplasts: isolation and molecular cloning of an enzyme catalyzing the conversion of 5,6‐epoxycarotenoid into ketocarotenoid

“…Chromoplast-specific proteins have also been observed by other authors (Hadjeb eta/., 1988;Smirra et al, 1993;Winkenbach et al, 1976). One of them, termed ChrA, has a molecular mass of 58 kDa and is a carotenoid-binding protein (Cervantes-Cervantes et al, 1990).…”

Microtubule-like inclusions in isolates of the blue-green bacteria Anabaena and Nostoc.

“…In chromoplasts of Trapaealum majus L. tubular structures 15 to 20nm in diameter are observed which are shown, when analyzed, to consist of a core of carotenoids and their esters coated by a monolayer of acyl lipids and proteins (Winkenbach et al 1976). It is possible that the structures reported here may be related to these reported plastid structures.…”