Common evolutionary origin

Related Proteins Share a Common Evolutionary Origin... 

Bui ETN, Bradley PJ, Johnson PJ. 1996. A common evolutionary origin for mitochondria and hydrogenosomes. Proc Nat Acad Sci USA 93 9651-6. 

The minimal functional unit (quite well conserved among all rubiscos) is a homodimer in which the active sites are located at the subunit interface. Residues from both subunits contribute to each active site, which is illustrated in Color Plate 8. All known forms (at present, four different types) consist of these basic dimeric units which are arranged into various larger multimer arrays—dimers, tetramers and even pentamers. The different forms of rubisco all have a common evolutionary origin and existing solid-state structures of the active sites are nearly superimposable. ... 

Bui TT, Bradley PJ, Johnson PJ (1996) A common evolutionary origin for mitochondria and hydrogenosomes. Proc Natl Acad Sci USA 93 9651-9656 Burri L, Williams BA, Bursae D, Lithgow T, Keeling PJ (2006) Microsporidia mitosomes retain elements of the general mitochondrial targeting system. Proc Natl Acad Sci USA... 

The four forms of hexokinase found in mammalian tissues are but one example of a common biological situation the same reaction catalyzed by two or more different molecular forms of an enzyme. These multiple forms, called isozymes or isoenzymes, may occur in the same species, in the same tissue, or even in the same cell. The different forms of the enzyme generally differ in kinetic or regulatory properties, in the cofactor they use (NADH or NADPH for dehydrogenase isozymes, for example), or in their subcellular distribution (soluble or membrane-bound). Isozymes may have similar, but not identical, amino acid sequences, and in many cases they clearly share a common evolutionary origin. 

One would expect little room for variation in the genetic code. Even a single amino acid substitution can have profoundly deleterious effects on the structure of a protein. Nevertheless, variations in the code do occur in some organisms, and they are both interesting and instructive. The types of variation and their rarity provide powerful evidence for a common evolutionary origin of all living things. 

Genetic analyses show that also the Chi a-binding proteins of red algae must be considered members of the LHC superfamily, even though they bind only Chi a and are associated only with PS I. [24] This shows that PBS (associated primarily with PS II) and membrane-intrinsic antennas of the LHC superfamily could coexist in the same chloroplast, and strongly supports a common evolutionary origin for all chloroplasts. [25]... 

Bui ET, Bradley PJ, Johnson PJ (1996) A common evolutionary origin for mitochondria and hydrogenosomes. Proc Natl Acad Sci USA 93 9651-9656 Campuzano V, Montermini L, Molto MD, Pianese L, Cossee M, Cavalcanti F, Monros E, Rodius F, Duclos F, Monticelli A, Zara F, Canizares J, Koutnikova H, Bidichandani SI, Gellera C, Brice A, Trouillas P, DeMichele G, Filla A, DeFrutos R, Palau F, Patel PI, DiDonato S, Mandel JL, Cocozza S, Koenig M, Pandolfo M (1996) Friedreich s ataxia autosomal recessive disease caused by an intronic GAA triplet repeat expansion. Science 271 1423-1427... 

The variety of aldehyde oxidases discovered in other plants have similarities to the maize enzyme, but also have some very important differences. Enzymes contained in a cell wall fraction from barley seedlings were able to oxidize IAAld to form IAA at a pH optimum of 7 and Km of 5 pmol 1 1, which was very similar to the enzyme found in maize.113 Two aldehyde oxidases from potato have also been identified 101 they had a similar pH optimum (between 7 and 8), but preferred aliphatic aldehydes to aromatic aldehydes. Although oat and cucumber aldehyde oxidases have been shown to oxidize IAAld to produce IAA,102 114 the oat enzyme had a lower pH optimum and higher Km than the maize enzyme, and the cucumber enzyme was inhibited by synthetic auxin and activated by 2-mercaptoethanol, which was not true for the maize enzyme. The difference in the enzymes makes it difficult to envision a common evolutionary origin for the IAAld pathway in plants if these particular enzymes are involved in each case. 

N. J. Patron and P. J. Keeling, Common evolutionary origin of starch biosynthetic enzymes in green and red algae,./. Phycol., 41 (2005) 1131-1141. 

Amazingly, and despite these seemingly major differences, the RNR a polypeptides plausibly have a common evolutionary origin with a preserved structural core comprised of two antiparallel five-stranded P/a halfbarrels (Figure 1). The resulting ten-stranded P/a barrel is wide enough to accom-... 

A result emerging from the genetic analysis of selenoproteins was the discovery that selenocysteine is the 21st amino acid encoded in DNA. Its insertion is directed by an in-frame UGA codon in the selenoprotein mRNA. UGA is used for this purpose in all three lines of descent (bacteria, archaea, and eukarya) The consistent use of UGA as a signal points to a common evolutionary origin of the selenocysteine coding system. 

---