1993
DOI: 10.1073/pnas.90.19.8929
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Site-specific and compensatory mutations imply unexpected pathways for proton delivery to the QB binding site of the photosynthetic reaction center.

Abstract: In photosynthetic reaction centers, a quinone molecule, QB, is the terminal acceptor in light-induced electron ransfer. The protonatable residues Glu-L212 and have been implicated in the binding of QB and in proton tr_aner to QB anions generated by electron transfer from the primary quinone QA. Here we report the details of the construction of the Ala-L212/Ala-L213 double mutant strain by site-specific mutagenesis and show that its photosynthetic incompetence is due to an inability to deliver protons to the Q… Show more

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Cited by 72 publications
(81 citation statements)
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“…This result suggests that the actual PT pathway in wild type bRC is more delocalized (6,15,51), involving not only the seven residues considered before (His-H126, His-H128, Asp-M17, Asp-L210, Glu-L212, Asp-L213, and Ser-L223). To interpret the metal binding influence and our calculated pK a values, we assume that bRC possesses a delocalized PT network as proposed in Refs.…”
Section: Resultsmentioning
confidence: 69%
“…This result suggests that the actual PT pathway in wild type bRC is more delocalized (6,15,51), involving not only the seven residues considered before (His-H126, His-H128, Asp-M17, Asp-L210, Glu-L212, Asp-L213, and Ser-L223). To interpret the metal binding influence and our calculated pK a values, we assume that bRC possesses a delocalized PT network as proposed in Refs.…”
Section: Resultsmentioning
confidence: 69%
“…In RCs with the mutation Glu H173 3 Gln (mutant H173EQ), the second electron transfer was also strongly inhibited but could be fully rescued by azide (24). However, it was not clear in these cases if the recovery was due to a proton delivery function of the added acid species, N 3 H (31), or an electrostatic effect of the bound anion, N 3 Ϫ (24), as has been proposed for the mechanism of many second site revertants to this and other primary lesions (32)(33)(34)(35)(36). Paddock and coworkers have studied RCs mutated at a putative H ϩ entry site on the protein surface, which are substantially impaired in proton uptake at elevated pH (25,37).…”
Section: From the Department Of Biochemistry And Center For Biophysicmentioning
confidence: 97%
“…1992b(Hanson et aI. , 1993Mar6ti et al 1994), and we have characterized a number of phenotypic revertants of this strain that have regained this function (Hanson et al DK Hanson & M Schiffer 1993;Mar6ti et al 1994), and preliminary characterization of two phenotypic revertants of the M246-iM247ED strain has also been reported previously (Laible et al 1997). Here we describe phenotypic revertants derived from the RQ quadruple mutant, an RC in which the important sequence asymmetry at these positions in the QA and QB binding sites has been reversed.…”
mentioning
confidence: 76%
“…The quadruple mutant RQ was constructed by ligating L and M gene segments from the previously-constructed L212-L213AA (Hanson et al 1993) and M246-247ED (Laible et al 1997) site-specific mutants. Cultures derived from independent colonies of the RQ strain were grown under chemoheterotrophic conditions.…”
Section: Methodsmentioning
confidence: 99%