Plant mitochondria contain at least two i-AAA-like complexes.
The FtsH proteases, also called AAA proteases, are membrane-bound ATP-dependent metalloproteases. The Arabidopsis genome contains a total of 12 FtsH-like genes. Two of them, AtFtsH4 and AtFtsH11, encode proteins with a high similarity to Yme1p, a subunit of the i-AAA complex in yeast mitochondria. Phylogenetic analysis groups the AtFtsH4, AtFtsH11 and Yme1 proteins together, with AtFtsH4 being the most similar to Yme1. Using immunological method we demonstrate here that AtFtsH4 is an exclusively mitochondrial protein while AtFtsH11 is found in both chloroplasts and mitochondria. AtFtsH4 and AtFtsH11 proteases are integral parts of the inner mitochondrial membrane and expose their catalytic sites towards the intermembrane space, same as yeast i-AAA. Database searches revealed that orthologs of AtFtsH4 and AtFtsH11 are present in both monocotyledonous and dicotyledonous plants. The two plant i-AAA proteases differ significantly in their termini: the FtsH4 proteins have a characteristic alanine stretch at the C-terminal end while FtsH11s have long N-terminal extensions. Blue-native gel electrophoresis revealed that AtFtsH4 and AtFtsH11 form at least two complexes with apparent molecular masses of about 1500 kDa. This finding implies that plants, in contrast to fungi and metazoa, have more than one complex with a topology similar to that of yeast i-AAA.
Urantowka
Adam
A
Laboratory of Cell Molecular Biology, Institute of Biochemistry and Molecular Biology, University of Wroclaw, Przybyszewskiego 63/77, 51-148, Wroclaw, Poland.
Knorpp
Carina
C
Olczak
Teresa
T
Kolodziejczak
Marta
M
Janska
Hanna
H
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D007425:Intracellular Membranes / Q000378:metabolism; D045726:Metalloproteases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation; D010802:Phylogeny; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; C036483:T-DNA; C506772:FtsH11 protein, Arabidopsis; C506771:FtsH4 protein, Arabidopsis; D045726:Metalloproteases