Understanding the structure and function of catalases: clues from molecular evolution and in vitro mutagenesis

Abstract

This review gives an overview about the structural organisation of different evolutionary lines of all enzymes capable of efficient dismutation of hydrogen peroxide. Major potential applications in biotechnology and clinical medicine justify further investigations. According to structural and functional similarities catalases can be divided in three subgroups. Typical catalases are homotetrameric haem proteins. The three-dimensional structure of six representatives has been resolved to atomic resolution. The central core of each subunit reveals a characteristic "catalase fold", extremely well conserved among this group. In the native tetramer structure pairs of subunits tightly interact via exchange of their N-terminal arms. This pseudo-knot structures implies a highly ordered assembly pathway. A minor subgroup ("large catalases") possesses an extra flavodoxin-like C-terminal domain. A > or = 25 A long channel leads from the enzyme surface to the deeply buried active site. It enables rapid and selective diffusion of the substrates to the active center. In several catalases NADPH is tightly bound close to the surface. This cofactor may prevent and reverse the formation of compound II, an inactive reaction intermediate. Bifunctional catalase-peroxidase are haem proteins which probably arose via gene duplication of an ancestral peroxidase gene. No detailed structural information is currently available. Even less is know about manganese catalases. Their di-manganese reaction centers may be evolutionary.

Cloning and allelic variation of two novel catalase genes (SoCAT-1andSsCAT-1) inSaccharum officinarumL. andSaccharum spontaneumL.

“…Based on gene structure and sequence, Zmocky and Koller [34] divided CATs into three subgroups, namely, …”

“…[8,9] As it contains four small subunits (55À69 kDa) and binds to four protoheme IX (protoheme b) groups, CAT forms a tetramer complex. [34] In eukaroytes, CATs are localized in peroxisomes. In our study, the predicted structures and functions of the proteins encoded by SoCAT-1a, SoCAT-1b, SsCAT-1a and SsCAT1b are in accordance with their expected biological role.…”

A minor catalase/peroxidase from Burkholderia cenocepacia is required for normal aconitase activity

“…Catalase, an enzyme found in both prokaryotes and eukaryotes, detoxifies H 2 O 2 into water and oxygen (Zamocky & Koller, 1999), and it can be grouped into three distinct enzyme families: mono-functional catalases (HPII class), bifunctional catalase/peroxidases (HPI class), and manganese-dependent catalases (Switala & Loewen, 2002;Zamocky & Koller, 1999;Zamocky et al, 2000). Bifunctional catalase/peroxidases are haem co-factored enzymes that have been described in simple eukaryotes and prokaryotes, and are evolutionarily linked to plant peroxidases (Zamocky & Koller, 1999;Zamocky et al, 2000). This class of enzymes has been associated with virulence in various bacterial pathogens, including Legionella pneumophila and Agrobacterium tumefaciens (Bandyopadhyay & Steinman, 1998Bandyopadhyay et al, 2003;Xu & Pan, 2000).…”

Protection Against Oxidative Stress and “IGF-I Deficiency Conditions”

“…CAT is a common antioxidant enzymes found in nearly all-living organisms that are exposed to oxygen and they can also remove organic H2O2 to oxidize toxins including phenols, formic acid, and hydroperoxides. CAT is present only or primarily in the peroxisome fraction and is absent in mitochondria of mammalian cells, except rat heart mitochondria [54]. Therefore, the only enzymatic defense system against hydrogen peroxide in mitochondria is the glutathione redox cycle system.…”