Converting RFC 2822 "timestamp" to timestampz

I have a RFC2822 timestamp (example: Thu, 21 Dec 2000 16:01:07 +0200).
I need to convert it to "timestampz" but I stumbled on the timezone
conversion. The code follows:

$timestamp = date( 'Y-m-d H:i:s O', strtotime( $rfc2822_timestamp) );

Unfortunately the supported formats for timezone in PHP and PostgreSQL
differs. Pgsql requires zone name or offset in the format "H:M"
(http://www.postgresql.org/docs/8.0/static/datatype-datetime.html#DATATYPE-TIMEZONE-TABLE).
The "date" function in PHP (versions up to 5.0) supports the following
two formats: "Difference to Greenwich time (GMT) in hours. Example:
+0200" and "Timezone offset in seconds: -43200 through 43200".

Of course I could play a little bit with last number (converting it to
"hours:minutes") but it seems unnatural. Am I missing something?

--
Milen A. Radev