46
V. K. Kannaujiya et al.
3.3 Occurrence and Distribution of Phycobiliproteins
PBPs are the major antennae complex of rods subunits stacked biliproteins with
linear tetrapyrrole chromophore which is covalently bound to cysteine residue (Adir
2005, Su et al. 2010, Watanabe and Ikeuchi 2013, Kannaujiya and Sinha 2015).
More than ten different PBPs have been detected in cyanobacteria and red algae
(Stadnichuk, and Tropin 2017). There are large numbers of cyanobacteria having a
different composition of PBPs (Table 3.1).
3.4 Chromophores
PBPs are chemically similar to bile pigments, thus it is called phycobilins. Pigments
with the chemical structure of bilins are also found in bacteria of different habitats,
mushrooms, higher plants, and a range of invertebrates. Along with PBPs, bilins
are enriched with cofactors of different proteins such as leghemoglobin in the root
nodules of beans and phytochromes of plants. Hemoglobin derived pigments are
also found in spiders, myriapods, and other arthropod tissues, the fins and muscles
of fishes, and coral skeleton (Rüdiger and Scheer 1983). Phycobilins are assigned to
linear tetrapyrroles, which contain four pyrrole rings A, B, C, and D connected by
single carbon bridges. The pyrrole rings A and D, contains one oxygen atom whereas
middle pyrrole rings, B and C, are associated with propionic acid residues (Glazer
1989). The phycoerythrobilin and phycourobilin incorporated in phycoerythrins can
have a second covalent bond with the protein in the D ring.
3.5 Biosynthesis
The core biosynthetic pathway of PBPs has followed the similar route as tetrapyrroles
biosynthesis. The core mechanism of tetrapyrroles biosynthesis has been originated
from evolution of photosynthetic bacteria. There are more than 19 enzymes involved
in the core pathway of conversion to initial precursor protoporphyrin IX from glutamate (Fujita et al. 2015). Certain enzymes including uroporphyrinogen synthase,
hydroxymethylbilane, hydroxymethylbilane synthase, porphobilinogen, and porphobilinogen synthase are extremely conserved from prokaryotes to eukaryotes (Dailey
et al. 2017). Recently, several pathways were found in bacteria related to heme
biosynthesis in higher plants. A set of enzymes used for catalytic conversion from
coproporphyrin intermediates in Gram-positive bacteria, (Dailey et al. 2015, Lobo
et al. 2015, Dailey and Gerdes 2015) whereas protoporphyrin intermediate in Gramnegative bacteria were found for biosynthesis of heme (Dailey et al. 2015). However,
certain sulfate-reducing bacteria and archaea have utilized another intermediate such
as siroheme for molecular conversion to protoheme (Kuhner et al. 2014). There is
V. K. Kannaujiya et al.
3.3 Occurrence and Distribution of Phycobiliproteins
PBPs are the major antennae complex of rods subunits stacked biliproteins with
linear tetrapyrrole chromophore which is covalently bound to cysteine residue (Adir
2005, Su et al. 2010, Watanabe and Ikeuchi 2013, Kannaujiya and Sinha 2015).
More than ten different PBPs have been detected in cyanobacteria and red algae
(Stadnichuk, and Tropin 2017). There are large numbers of cyanobacteria having a
different composition of PBPs (Table 3.1).
3.4 Chromophores
PBPs are chemically similar to bile pigments, thus it is called phycobilins. Pigments
with the chemical structure of bilins are also found in bacteria of different habitats,
mushrooms, higher plants, and a range of invertebrates. Along with PBPs, bilins
are enriched with cofactors of different proteins such as leghemoglobin in the root
nodules of beans and phytochromes of plants. Hemoglobin derived pigments are
also found in spiders, myriapods, and other arthropod tissues, the fins and muscles
of fishes, and coral skeleton (Rüdiger and Scheer 1983). Phycobilins are assigned to
linear tetrapyrroles, which contain four pyrrole rings A, B, C, and D connected by
single carbon bridges. The pyrrole rings A and D, contains one oxygen atom whereas
middle pyrrole rings, B and C, are associated with propionic acid residues (Glazer
1989). The phycoerythrobilin and phycourobilin incorporated in phycoerythrins can
have a second covalent bond with the protein in the D ring.
3.5 Biosynthesis
The core biosynthetic pathway of PBPs has followed the similar route as tetrapyrroles
biosynthesis. The core mechanism of tetrapyrroles biosynthesis has been originated
from evolution of photosynthetic bacteria. There are more than 19 enzymes involved
in the core pathway of conversion to initial precursor protoporphyrin IX from glutamate (Fujita et al. 2015). Certain enzymes including uroporphyrinogen synthase,
hydroxymethylbilane, hydroxymethylbilane synthase, porphobilinogen, and porphobilinogen synthase are extremely conserved from prokaryotes to eukaryotes (Dailey
et al. 2017). Recently, several pathways were found in bacteria related to heme
biosynthesis in higher plants. A set of enzymes used for catalytic conversion from
coproporphyrin intermediates in Gram-positive bacteria, (Dailey et al. 2015, Lobo
et al. 2015, Dailey and Gerdes 2015) whereas protoporphyrin intermediate in Gramnegative bacteria were found for biosynthesis of heme (Dailey et al. 2015). However,
certain sulfate-reducing bacteria and archaea have utilized another intermediate such
as siroheme for molecular conversion to protoheme (Kuhner et al. 2014). There is